[syzbot] [rdma?] [s390?] [net?] KASAN: null-ptr-deref Read in smc_tcp_syn_recv_sock

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 850925a8133c Merge tag '9p-for-6.12-rc5' of https://github..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1227aa87980000
kernel config: https://syzkaller.appspot.com/x/.config?x=17c0d505695d6b0
dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15489230580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/6d8177e17058/disk-850925a8.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5d88252f39ff/vmlinux-850925a8.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7a675a61b90d/bzImage-850925a8.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+827ae2...@syzkaller.appspotmail.com

TCP: request_sock_TCP: Possible SYN flooding on port [::]:20002. Sending cookies.
TCP: request_sock_TCP: Possible SYN flooding on port [::]:20002. Sending cookies.
==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
BUG: KASAN: null-ptr-deref in smc_tcp_syn_recv_sock+0xa7/0x4b0 net/smc/af_smc.c:131
Read of size 4 at addr 00000000000009d4 by task syz.4.10809/28966

CPU: 1 UID: 0 PID: 28966 Comm: syz.4.10809 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
kasan_report+0xd9/0x110 mm/kasan/report.c:601
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
instrument_atomic_read include/linux/instrumented.h:68 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
smc_tcp_syn_recv_sock+0xa7/0x4b0 net/smc/af_smc.c:131
tcp_get_cookie_sock+0xd5/0x790 net/ipv4/syncookies.c:204
cookie_v4_check+0xcf8/0x1d40 net/ipv4/syncookies.c:485
tcp_v4_cookie_check net/ipv4/tcp_ipv4.c:1864 [inline]
tcp_v4_do_rcv+0x98e/0xa90 net/ipv4/tcp_ipv4.c:1923
tcp_v4_rcv+0x3cd2/0x4390 net/ipv4/tcp_ipv4.c:2340
ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:460 [inline]
ip_rcv_finish net/ipv4/ip_input.c:449 [inline]
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:569
__netif_receive_skb_one_core+0x199/0x1e0 net/core/dev.c:5666
__netif_receive_skb+0x1d/0x160 net/core/dev.c:5779
process_backlog+0x443/0x15f0 net/core/dev.c:6111
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:6775
napi_poll net/core/dev.c:6844 [inline]
net_rx_action+0xa92/0x1010 net/core/dev.c:6966
handle_softirqs+0x216/0x8f0 kernel/softirq.c:554
do_softirq kernel/softirq.c:455 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:442
</IRQ>
<TASK>
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:382
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]
__dev_queue_xmit+0x887/0x4350 net/core/dev.c:4455
dev_queue_xmit include/linux/netdevice.h:3094 [inline]
neigh_hh_output include/net/neighbour.h:526 [inline]
neigh_output include/net/neighbour.h:540 [inline]
ip_finish_output2+0x16d7/0x2530 net/ipv4/ip_output.c:236
__ip_finish_output net/ipv4/ip_output.c:314 [inline]
__ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:296
ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:324
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:434
dst_output include/net/dst.h:450 [inline]
ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:130
__ip_queue_xmit+0x747/0x1940 net/ipv4/ip_output.c:536
__tcp_transmit_skb+0x2a4c/0x3dc0 net/ipv4/tcp_output.c:1466
__tcp_send_ack.part.0+0x390/0x720 net/ipv4/tcp_output.c:4268
__tcp_send_ack net/ipv4/tcp_output.c:4274 [inline]
tcp_send_ack+0x82/0xa0 net/ipv4/tcp_output.c:4274
tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6576 [inline]
tcp_rcv_state_process+0x4332/0x4f30 net/ipv4/tcp_input.c:6770
tcp_v4_do_rcv+0x1ad/0xa90 net/ipv4/tcp_ipv4.c:1938
sk_backlog_rcv include/net/sock.h:1115 [inline]
__release_sock+0x31b/0x400 net/core/sock.c:3072
release_sock+0x5a/0x220 net/core/sock.c:3626
mptcp_connect+0xc14/0xee0 net/mptcp/protocol.c:3800
__inet_stream_connect+0x3ca/0x1020 net/ipv4/af_inet.c:679
inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:750
__sys_connect_file+0x150/0x190 net/socket.c:2071
__sys_connect+0x147/0x180 net/socket.c:2088
__do_sys_connect net/socket.c:2098 [inline]
__se_sys_connect net/socket.c:2095 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2095
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f68acb7e719
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f68ada08038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f68acd35f80 RCX: 00007f68acb7e719
RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f68acbf132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f68acd35f80 R15: 00007ffdea14cb48
</TASK>
==================================================================
Oops: general protection fault, probably for non-canonical address 0xdffffc000000013a: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x00000000000009d0-0x00000000000009d7]
CPU: 1 UID: 0 PID: 28966 Comm: syz.4.10809 Tainted: G B 6.12.0-rc4-syzkaller-00261-g850925a8133c #0
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline]
RIP: 0010:smc_tcp_syn_recv_sock+0xb8/0x4b0 net/smc/af_smc.c:131
Code: ad d4 09 00 00 be 04 00 00 00 44 8b bb 1c 04 00 00 4c 89 ef e8 69 94 2e f7 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 14 02 4c 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 34
RSP: 0018:ffffc90000a18668 EFLAGS: 00010217
RAX: dffffc0000000000 RBX: ffff88805b9cb600 RCX: ffffffff814e856f
RDX: 000000000000013a RSI: ffffffff81ee031e RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 6e696c6261736944 R12: ffff88807df5bd00
R13: 00000000000009d4 R14: ffffc90000a186e8 R15: 0000000000000000
FS: 00007f68ada086c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f68ad9e7d58 CR3: 000000005e3fa000 CR4: 0000000000350ef0
Call Trace:
<IRQ>
tcp_get_cookie_sock+0xd5/0x790 net/ipv4/syncookies.c:204
cookie_v4_check+0xcf8/0x1d40 net/ipv4/syncookies.c:485
tcp_v4_cookie_check net/ipv4/tcp_ipv4.c:1864 [inline]
tcp_v4_do_rcv+0x98e/0xa90 net/ipv4/tcp_ipv4.c:1923
tcp_v4_rcv+0x3cd2/0x4390 net/ipv4/tcp_ipv4.c:2340
ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:460 [inline]
ip_rcv_finish net/ipv4/ip_input.c:449 [inline]
NF_HOOK include/linux/netfilter.h:314 [inline]
NF_HOOK include/linux/netfilter.h:308 [inline]
ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:569
__netif_receive_skb_one_core+0x199/0x1e0 net/core/dev.c:5666
__netif_receive_skb+0x1d/0x160 net/core/dev.c:5779
process_backlog+0x443/0x15f0 net/core/dev.c:6111
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:6775
napi_poll net/core/dev.c:6844 [inline]
net_rx_action+0xa92/0x1010 net/core/dev.c:6966
handle_softirqs+0x216/0x8f0 kernel/softirq.c:554
do_softirq kernel/softirq.c:455 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:442
</IRQ>
<TASK>
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:382
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline]
__dev_queue_xmit+0x887/0x4350 net/core/dev.c:4455
dev_queue_xmit include/linux/netdevice.h:3094 [inline]
neigh_hh_output include/net/neighbour.h:526 [inline]
neigh_output include/net/neighbour.h:540 [inline]
ip_finish_output2+0x16d7/0x2530 net/ipv4/ip_output.c:236
__ip_finish_output net/ipv4/ip_output.c:314 [inline]
__ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:296
ip_finish_output+0x31/0x310 net/ipv4/ip_output.c:324
NF_HOOK_COND include/linux/netfilter.h:303 [inline]
ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:434
dst_output include/net/dst.h:450 [inline]
ip_local_out+0x33e/0x4a0 net/ipv4/ip_output.c:130
__ip_queue_xmit+0x747/0x1940 net/ipv4/ip_output.c:536
__tcp_transmit_skb+0x2a4c/0x3dc0 net/ipv4/tcp_output.c:1466
__tcp_send_ack.part.0+0x390/0x720 net/ipv4/tcp_output.c:4268
__tcp_send_ack net/ipv4/tcp_output.c:4274 [inline]
tcp_send_ack+0x82/0xa0 net/ipv4/tcp_output.c:4274
tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6576 [inline]
tcp_rcv_state_process+0x4332/0x4f30 net/ipv4/tcp_input.c:6770
tcp_v4_do_rcv+0x1ad/0xa90 net/ipv4/tcp_ipv4.c:1938
sk_backlog_rcv include/net/sock.h:1115 [inline]
__release_sock+0x31b/0x400 net/core/sock.c:3072
release_sock+0x5a/0x220 net/core/sock.c:3626
mptcp_connect+0xc14/0xee0 net/mptcp/protocol.c:3800
__inet_stream_connect+0x3ca/0x1020 net/ipv4/af_inet.c:679
inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:750
__sys_connect_file+0x150/0x190 net/socket.c:2071
__sys_connect+0x147/0x180 net/socket.c:2088
__do_sys_connect net/socket.c:2098 [inline]
__se_sys_connect net/socket.c:2095 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2095
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f68acb7e719
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f68ada08038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007f68acd35f80 RCX: 00007f68acb7e719
RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000004
RBP: 00007f68acbf132e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f68acd35f80 R15: 00007ffdea14cb48
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:arch_atomic_read arch/x86/include/asm/atomic.h:23 [inline]
RIP: 0010:raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
RIP: 0010:atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline]
RIP: 0010:smc_tcp_syn_recv_sock+0xb8/0x4b0 net/smc/af_smc.c:131
Code: ad d4 09 00 00 be 04 00 00 00 44 8b bb 1c 04 00 00 4c 89 ef e8 69 94 2e f7 4c 89 ea 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <0f> b6 14 02 4c 89 e8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 34
RSP: 0018:ffffc90000a18668 EFLAGS: 00010217
RAX: dffffc0000000000 RBX: ffff88805b9cb600 RCX: ffffffff814e856f
RDX: 000000000000013a RSI: ffffffff81ee031e RDI: 0000000000000007
RBP: 0000000000000000 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000000 R11: 6e696c6261736944 R12: ffff88807df5bd00
R13: 00000000000009d4 R14: ffffc90000a186e8 R15: 0000000000000000
FS: 00007f68ada086c0(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f68ad9e7d58 CR3: 000000005e3fa000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 09 00 or %eax,(%rax)
2: 00 be 04 00 00 00 add %bh,0x4(%rsi)
8: 44 8b bb 1c 04 00 00 mov 0x41c(%rbx),%r15d
f: 4c 89 ef mov %r13,%rdi
12: e8 69 94 2e f7 call 0xf72e9480
17: 4c 89 ea mov %r13,%rdx
1a: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
21: fc ff df
24: 48 c1 ea 03 shr $0x3,%rdx
* 28: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction
2c: 4c 89 e8 mov %r13,%rax
2f: 83 e0 07 and $0x7,%eax
32: 83 c0 03 add $0x3,%eax
35: 38 d0 cmp %dl,%al
37: 7c 08 jl 0x41
39: 84 d2 test %dl,%dl
3b: 0f .byte 0xf
3c: 85 .byte 0x85
3d: 34 .byte 0x34


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
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If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

[I Hsin Cheng]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 850925a8133c

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 3e6cb35baf25..41f8dcd734a6 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -127,6 +127,8 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
struct sock *child;

smc = smc_clcsock_user_data(sk);
+ if (!smc)
+ goto drop;

if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
sk->sk_max_ack_backlog)

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
possible deadlock in smc_release

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc4-syzkaller-00261-g850925a8133c-dirty #0 Not tainted
------------------------------------------------------
syz.1.6963/21920 is trying to acquire lock:
ffff888033c0b750 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: touch_work_lockdep_map kernel/workqueue.c:3895 [inline]
ffff888033c0b750 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: start_flush_work kernel/workqueue.c:4149 [inline]
ffff888033c0b750 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}, at: __flush_work+0x46d/0xc30 kernel/workqueue.c:4181

but task is already holding lock:
ffff88805fe88dd8 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x378/0x5f0 net/smc/af_smc.c:338

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (sk_lock-AF_SMC/1){+.+.}-{0:0}:
lock_sock_nested+0x3a/0xf0 net/core/sock.c:3611
smc_listen_out+0x1fa/0x490 net/smc/af_smc.c:1907
smc_listen_out_connected net/smc/af_smc.c:1927 [inline]
smc_listen_work+0x571/0x50c0 net/smc/af_smc.c:2441
process_one_work+0x9c8/0x1ba0 kernel/workqueue.c:3229
process_scheduled_works kernel/workqueue.c:3310 [inline]
worker_thread+0x6c8/0xf00 kernel/workqueue.c:3391
kthread+0x2c4/0x3a0 kernel/kthread.c:389
ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

-> #0 ((work_completion)(&new_smc->smc_listen_work)){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
touch_work_lockdep_map kernel/workqueue.c:3895 [inline]
start_flush_work kernel/workqueue.c:4149 [inline]
__flush_work+0x477/0xc30 kernel/workqueue.c:4181
__cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4337
smc_clcsock_release+0x5f/0xe0 net/smc/smc_close.c:29
__smc_release+0x5c2/0x880 net/smc/af_smc.c:303
smc_close_non_accepted+0xda/0x200 net/smc/af_smc.c:1839
smc_close_cleanup_listen net/smc/smc_close.c:45 [inline]
smc_close_active+0xc3c/0x1070 net/smc/smc_close.c:225
__smc_release+0x634/0x880 net/smc/af_smc.c:279
smc_release+0x1fc/0x5f0 net/smc/af_smc.c:346
__sock_release+0xb3/0x270 net/socket.c:658
sock_close+0x1c/0x30 net/socket.c:1426
__fput+0x3f9/0xb60 fs/file_table.c:431
task_work_run+0x151/0x250 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sk_lock-AF_SMC/1);
lock((work_completion)(&new_smc->smc_listen_work));
lock(sk_lock-AF_SMC/1);
lock((work_completion)(&new_smc->smc_listen_work));

*** DEADLOCK ***

3 locks held by syz.1.6963/21920:
#0: ffff8880746ea008 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:815 [inline]
#0: ffff8880746ea008 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x270 net/socket.c:657
#1: ffff88805fe88dd8 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x378/0x5f0 net/smc/af_smc.c:338
#2: ffffffff8e1b8380 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
#2: ffffffff8e1b8380 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
#2: ffffffff8e1b8380 (rcu_read_lock){....}-{1:2}, at: start_flush_work kernel/workqueue.c:4123 [inline]
#2: ffffffff8e1b8380 (rcu_read_lock){....}-{1:2}, at: __flush_work+0x103/0xc30 kernel/workqueue.c:4181

stack backtrace:
CPU: 0 UID: 0 PID: 21920 Comm: syz.1.6963 Not tainted 6.12.0-rc4-syzkaller-00261-g850925a8133c-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
<TASK>

__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120

print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
touch_work_lockdep_map kernel/workqueue.c:3895 [inline]
start_flush_work kernel/workqueue.c:4149 [inline]
__flush_work+0x477/0xc30 kernel/workqueue.c:4181
__cancel_work_sync+0x10c/0x130 kernel/workqueue.c:4337
smc_clcsock_release+0x5f/0xe0 net/smc/smc_close.c:29
__smc_release+0x5c2/0x880 net/smc/af_smc.c:303
smc_close_non_accepted+0xda/0x200 net/smc/af_smc.c:1839
smc_close_cleanup_listen net/smc/smc_close.c:45 [inline]
smc_close_active+0xc3c/0x1070 net/smc/smc_close.c:225
__smc_release+0x634/0x880 net/smc/af_smc.c:279
smc_release+0x1fc/0x5f0 net/smc/af_smc.c:346
__sock_release+0xb3/0x270 net/socket.c:658
sock_close+0x1c/0x30 net/socket.c:1426
__fput+0x3f9/0xb60 fs/file_table.c:431
task_work_run+0x151/0x250 kernel/task_work.c:239
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x27b/0x2a0 kernel/entry/common.c:218
do_syscall_64+0xda/0x250 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f851fb7e719

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007f85208c6038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007f851fd35f80 RCX: 00007f851fb7e719
RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003
RBP: 00007f851fbf132e R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007f851fd35f80 R15: 00007ffea8200be8
</TASK>


Tested on:

commit: 850925a8 Merge tag '9p-for-6.12-rc5' of https://github..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=114cefb0580000

kernel config: https://syzkaller.appspot.com/x/.config?x=17c0d505695d6b0
dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=155d294c580000

[Arnaud Lecomte]

#syz test

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -123,11 +123,14 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
struct request_sock *req_unhash,
bool *own_req)
{
+ read_lock_bh(&((struct sock *)sk)->sk_callback_lock);
struct smc_sock *smc;
struct sock *child;
-

smc = smc_clcsock_user_data(sk);

+ if (!smc)
+ goto drop;

+

if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
sk->sk_max_ack_backlog)

goto drop;
@@ -148,9 +151,11 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
if (inet_csk(child)->icsk_af_ops == inet_csk(sk)->icsk_af_ops)
inet_csk(child)->icsk_af_ops = smc->ori_af_ops;
}
+ read_unlock_bh(&((struct sock *)sk)->sk_callback_lock);
return child;

drop:
+ read_unlock_bh(&((struct sock *)sk)->sk_callback_lock);
dst_release(dst);
tcp_listendrop(sk);
return NULL;
@@ -2613,7 +2618,7 @@ int smc_listen(struct socket *sock, int backlog)
int rc;

smc = smc_sk(sk);
- lock_sock(sk);
+ lock_sock(sock->sk);

rc = -EINVAL;
if ((sk->sk_state != SMC_INIT && sk->sk_state != SMC_LISTEN) ||
--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

possible deadlock in inet_child_forget

======================================================
WARNING: possible circular locking dependency detected

6.16.0-rc3-syzkaller-00329-gdfba48a70cb6-dirty #0 Not tainted
------------------------------------------------------
syz.3.22/6775 is trying to acquire lock:
ffff888031981170 (k-clock-AF_INET6){++.-}-{3:3}, at: sock_orphan include/net/sock.h:2075 [inline]
ffff888031981170 (k-clock-AF_INET6){++.-}-{3:3}, at: inet_child_forget+0x7e/0x2e0 net/ipv4/inet_connection_sock.c:1383

but task is already holding lock:

ffff888031980f58 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff888031980f58 (k-slock-AF_INET6){+.-.}-{3:3}, at: inet_csk_listen_stop+0x203/0x1090 net/ipv4/inet_connection_sock.c:1495

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (k-slock-AF_INET6){+.-.}-{3:3}:
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
sk_clone_lock+0x334/0x1330 net/core/sock.c:2499
inet_csk_clone_lock+0x2a/0x750 net/ipv4/inet_connection_sock.c:1232
tcp_create_openreq_child+0x34/0x1980 net/ipv4/tcp_minisocks.c:526
tcp_v4_syn_recv_sock+0x115/0x1250 net/ipv4/tcp_ipv4.c:1774
tcp_v6_syn_recv_sock+0x1353/0x2480 net/ipv6/tcp_ipv6.c:1382
smc_tcp_syn_recv_sock+0x24b/0x500 net/smc/af_smc.c:144
tcp_check_req+0x69d/0x1f80 net/ipv4/tcp_minisocks.c:874
tcp_v4_rcv+0x19b0/0x4650 net/ipv4/tcp_ipv4.c:2283

ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233

NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:469 [inline]
ip_rcv_finish net/ipv4/ip_input.c:447 [inline]
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:567
__netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5977
__netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
process_backlog+0x442/0x15e0 net/core/dev.c:6442
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414
napi_poll net/core/dev.c:7478 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605
handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
do_softirq kernel/softirq.c:480 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:467
__local_bh_enable_ip+0x100/0x120 kernel/softirq.c:407
local_bh_enable include/linux/bottom_half.h:33 [inline]
rcu_read_unlock_bh include/linux/rcupdate.h:910 [inline]
__dev_queue_xmit+0x8ab/0x43e0 net/core/dev.c:4740
dev_queue_xmit include/linux/netdevice.h:3355 [inline]
neigh_hh_output include/net/neighbour.h:523 [inline]
neigh_output include/net/neighbour.h:537 [inline]
ip_finish_output2+0xc38/0x21a0 net/ipv4/ip_output.c:235
__ip_finish_output net/ipv4/ip_output.c:313 [inline]
__ip_finish_output+0x49e/0x950 net/ipv4/ip_output.c:295
ip_finish_output+0x35/0x380 net/ipv4/ip_output.c:323
NF_HOOK_COND include/linux/netfilter.h:306 [inline]
ip_output+0x13b/0x2a0 net/ipv4/ip_output.c:433
dst_output include/net/dst.h:459 [inline]
ip_local_out net/ipv4/ip_output.c:129 [inline]
__ip_queue_xmit+0x1d7d/0x26c0 net/ipv4/ip_output.c:527
__tcp_transmit_skb+0x2686/0x3e90 net/ipv4/tcp_output.c:1479
__tcp_send_ack.part.0+0x3de/0x700 net/ipv4/tcp_output.c:4279
__tcp_send_ack net/ipv4/tcp_output.c:4285 [inline]
tcp_send_ack+0x84/0xa0 net/ipv4/tcp_output.c:4285
tcp_rcv_synsent_state_process net/ipv4/tcp_input.c:6632 [inline]
tcp_rcv_state_process+0x4236/0x4ed0 net/ipv4/tcp_input.c:6826
tcp_v4_do_rcv+0x1ad/0xa90 net/ipv4/tcp_ipv4.c:1948
sk_backlog_rcv include/net/sock.h:1148 [inline]
__release_sock+0x31b/0x400 net/core/sock.c:3213
release_sock+0x5a/0x220 net/core/sock.c:3767
mptcp_connect+0xccd/0xfe0 net/mptcp/protocol.c:3695
__inet_stream_connect+0x3c8/0x1020 net/ipv4/af_inet.c:677
inet_stream_connect+0x57/0xa0 net/ipv4/af_inet.c:748
__sys_connect_file+0x141/0x1a0 net/socket.c:2038
__sys_connect+0x13b/0x160 net/socket.c:2057
__do_sys_connect net/socket.c:2063 [inline]
__se_sys_connect net/socket.c:2060 [inline]
__x64_sys_connect+0x72/0xb0 net/socket.c:2060
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0x4c0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (k-clock-AF_INET6){++.-}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3168 [inline]
check_prevs_add kernel/locking/lockdep.c:3287 [inline]
validate_chain kernel/locking/lockdep.c:3911 [inline]
__lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
lock_acquire kernel/locking/lockdep.c:5871 [inline]
lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
__raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
_raw_write_lock_bh+0x33/0x40 kernel/locking/spinlock.c:334
sock_orphan include/net/sock.h:2075 [inline]
inet_child_forget+0x7e/0x2e0 net/ipv4/inet_connection_sock.c:1383
inet_csk_listen_stop+0x323/0x1090 net/ipv4/inet_connection_sock.c:1523
tcp_disconnect+0x18a4/0x1ec0 net/ipv4/tcp.c:3340
inet_shutdown+0x26f/0x440 net/ipv4/af_inet.c:935
smc_close_active+0xc2a/0x1070 net/smc/smc_close.c:223
__smc_release+0x634/0x880 net/smc/af_smc.c:282
smc_release+0x1fc/0x5f0 net/smc/af_smc.c:349
__sock_release+0xb3/0x270 net/socket.c:647
sock_close+0x1c/0x30 net/socket.c:1391
__fput+0x402/0xb70 fs/file_table.c:465
task_work_run+0x150/0x240 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100

entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

lock(k-slock-AF_INET6);
lock(k-clock-AF_INET6);
lock(k-slock-AF_INET6);
lock(k-clock-AF_INET6);

*** DEADLOCK ***

4 locks held by syz.3.22/6775:
#0: ffff888056c4b808 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
#0: ffff888056c4b808 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: __sock_release+0x86/0x270 net/socket.c:646
#1: ffff8880316dc758 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x378/0x5f0 net/smc/af_smc.c:341
#2: ffff888031983858 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline]
#2: ffff888031983858 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:905
#3: ffff888031980f58 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#3: ffff888031980f58 (k-slock-AF_INET6){+.-.}-{3:3}, at: inet_csk_listen_stop+0x203/0x1090 net/ipv4/inet_connection_sock.c:1495

stack backtrace:
CPU: 0 UID: 0 PID: 6775 Comm: syz.3.22 Not tainted 6.16.0-rc3-syzkaller-00329-gdfba48a70cb6-dirty #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120

print_circular_bug+0x275/0x350 kernel/locking/lockdep.c:2046
check_noncircular+0x14c/0x170 kernel/locking/lockdep.c:2178
check_prev_add kernel/locking/lockdep.c:3168 [inline]
check_prevs_add kernel/locking/lockdep.c:3287 [inline]
validate_chain kernel/locking/lockdep.c:3911 [inline]
__lock_acquire+0x126f/0x1c90 kernel/locking/lockdep.c:5240
lock_acquire kernel/locking/lockdep.c:5871 [inline]
lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5828
__raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
_raw_write_lock_bh+0x33/0x40 kernel/locking/spinlock.c:334
sock_orphan include/net/sock.h:2075 [inline]
inet_child_forget+0x7e/0x2e0 net/ipv4/inet_connection_sock.c:1383
inet_csk_listen_stop+0x323/0x1090 net/ipv4/inet_connection_sock.c:1523
tcp_disconnect+0x18a4/0x1ec0 net/ipv4/tcp.c:3340
inet_shutdown+0x26f/0x440 net/ipv4/af_inet.c:935
smc_close_active+0xc2a/0x1070 net/smc/smc_close.c:223
__smc_release+0x634/0x880 net/smc/af_smc.c:282
smc_release+0x1fc/0x5f0 net/smc/af_smc.c:349
__sock_release+0xb3/0x270 net/socket.c:647
sock_close+0x1c/0x30 net/socket.c:1391
__fput+0x402/0xb70 fs/file_table.c:465
task_work_run+0x150/0x240 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xeb/0x110 kernel/entry/common.c:114
exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
do_syscall_64+0x3f6/0x4c0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe73c37e719

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fe73d091038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fe73c535f80 RCX: 00007fe73c37e719

RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003

RBP: 00007fe73c3f132e R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007fe73c535f80 R15: 00007fff230025e8
</TASK>


Tested on:

commit: dfba48a7 Merge tag 'i2c-for-6.16-rc4' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16ce688c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=d3e0d55231e0c89c

dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1124c770580000

[Arnaud Lecomte]

#syz test

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c

@@ -126,8 +126,12 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,

struct smc_sock *smc;
struct sock *child;

+ lockdep_assert_held_read(&sk->sk_callback_lock);

smc = smc_clcsock_user_data(sk);

+ if (!smc)
+ goto drop;
+
if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
sk->sk_max_ack_backlog)
goto drop;

--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

WARNING in smc_tcp_syn_recv_sock

------------[ cut here ]------------
WARNING: CPU: 1 PID: 6792 at net/smc/af_smc.c:129 smc_tcp_syn_recv_sock+0x3f8/0x570 net/smc/af_smc.c:129
Modules linked in:
CPU: 1 UID: 0 PID: 6792 Comm: syz.1.16 Not tainted 6.16.0-rc3-syzkaller-gdfba48a70cb6-dirty #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025

RIP: 0010:smc_tcp_syn_recv_sock+0x3f8/0x570 net/smc/af_smc.c:129
Code: 48 8d bb f0 03 00 00 be 01 00 00 00 e8 21 c0 57 00 31 ff 89 c5 89 c6 e8 96 88 a2 f6 85 ed 0f 85 81 fc ff ff e8 49 8d a2 f6 90 <0f> 0b 90 e9 73 fc ff ff e8 3b 8d a2 f6 4c 89 fa 48 b8 00 00 00 00
RSP: 0018:ffffc90000a08780 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff888034d95e80 RCX: ffffffff8b198ffa
RDX: ffff88802825da00 RSI: ffffffff8b199007 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000001 R12: 0000000000000000
R13: ffff8880352e89e0 R14: ffffc90000a08850 R15: ffff888034d95e80
FS: 00007fba98e0c6c0(0000) GS:ffff888124ab5000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000020000040 CR3: 0000000032bf6000 CR4: 0000000000350ef0
Call Trace:
<IRQ>

tcp_check_req+0x69d/0x1f80 net/ipv4/tcp_minisocks.c:874
tcp_v4_rcv+0x19b0/0x4650 net/ipv4/tcp_ipv4.c:2283
ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:469 [inline]
ip_rcv_finish net/ipv4/ip_input.c:447 [inline]
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:567
__netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5977
__netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
process_backlog+0x442/0x15e0 net/core/dev.c:6442
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414
napi_poll net/core/dev.c:7478 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605
handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
do_softirq kernel/softirq.c:480 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:467

</IRQ>
<TASK>

RIP: 0033:0x7fba97f7e719

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fba98e0c038 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fba98135f80 RCX: 00007fba97f7e719

RDX: 0000000000000010 RSI: 0000000020000000 RDI: 0000000000000004

RBP: 00007fba97ff132e R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007fba98135f80 R15: 00007ffdbf9fe0b8

</TASK>


Tested on:

commit: dfba48a7 Merge tag 'i2c-for-6.16-rc4' of git://git.ker..
git tree: upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=1622a982580000

kernel config: https://syzkaller.appspot.com/x/.config?x=d3e0d55231e0c89c
dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=1097888c580000

[Arnaud Lecomte]

#syz test

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c

@@ -125,9 +125,12 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,

{
struct smc_sock *smc;
struct sock *child;

-
+ read_lock_bh(&((struct sock *)sk)->sk_callback_lock);

smc = smc_clcsock_user_data(sk);

+ if (!smc)
+ goto drop;
+
if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
sk->sk_max_ack_backlog)
goto drop;

@@ -148,9 +151,11 @@ static struct sock *smc_tcp_syn_recv_sock(const struct sock *sk,
if (inet_csk(child)->icsk_af_ops == inet_csk(sk)->icsk_af_ops)
inet_csk(child)->icsk_af_ops = smc->ori_af_ops;
}
+ read_unlock_bh(&((struct sock *)sk)->sk_callback_lock);
return child;

drop:
+ read_unlock_bh(&((struct sock *)sk)->sk_callback_lock);
dst_release(dst);
tcp_listendrop(sk);
return NULL;

--
2.43.0

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:

possible deadlock in inet_child_forget

======================================================
WARNING: possible circular locking dependency detected

6.16.0-rc3-syzkaller-gdfba48a70cb6-dirty #0 Not tainted
------------------------------------------------------
syz.2.23/6591 is trying to acquire lock:
ffff88805b87ac70 (k-clock-AF_INET6){++.-}-{3:3}, at: sock_orphan include/net/sock.h:2075 [inline]
ffff88805b87ac70 (k-clock-AF_INET6){++.-}-{3:3}, at: inet_child_forget+0x7e/0x2e0 net/ipv4/inet_connection_sock.c:1383

but task is already holding lock:

ffff88805b87aa58 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88805b87aa58 (k-slock-AF_INET6){+.-.}-{3:3}, at: inet_csk_listen_stop+0x203/0x1090 net/ipv4/inet_connection_sock.c:1495

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (k-slock-AF_INET6){+.-.}-{3:3}:
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:351 [inline]
sk_clone_lock+0x334/0x1330 net/core/sock.c:2499
inet_csk_clone_lock+0x2a/0x750 net/ipv4/inet_connection_sock.c:1232
tcp_create_openreq_child+0x34/0x1980 net/ipv4/tcp_minisocks.c:526
tcp_v4_syn_recv_sock+0x115/0x1250 net/ipv4/tcp_ipv4.c:1774
tcp_v6_syn_recv_sock+0x1353/0x2480 net/ipv6/tcp_ipv6.c:1382
smc_tcp_syn_recv_sock+0x24b/0x500 net/smc/af_smc.c:144

tcp_check_req+0x69d/0x1f80 net/ipv4/tcp_minisocks.c:874
tcp_v4_rcv+0x19b0/0x4650 net/ipv4/tcp_ipv4.c:2283
ip_protocol_deliver_rcu+0xba/0x4c0 net/ipv4/ip_input.c:205
ip_local_deliver_finish+0x316/0x570 net/ipv4/ip_input.c:233
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_local_deliver+0x18e/0x1f0 net/ipv4/ip_input.c:254
dst_input include/net/dst.h:469 [inline]
ip_rcv_finish net/ipv4/ip_input.c:447 [inline]
NF_HOOK include/linux/netfilter.h:317 [inline]
NF_HOOK include/linux/netfilter.h:311 [inline]
ip_rcv+0x2c3/0x5d0 net/ipv4/ip_input.c:567
__netif_receive_skb_one_core+0x197/0x1e0 net/core/dev.c:5977
__netif_receive_skb+0x1d/0x160 net/core/dev.c:6090
process_backlog+0x442/0x15e0 net/core/dev.c:6442
__napi_poll.constprop.0+0xba/0x550 net/core/dev.c:7414
napi_poll net/core/dev.c:7478 [inline]
net_rx_action+0xa9f/0xfe0 net/core/dev.c:7605
handle_softirqs+0x219/0x8e0 kernel/softirq.c:579
do_softirq kernel/softirq.c:480 [inline]
do_softirq+0xb2/0xf0 kernel/softirq.c:467

4 locks held by syz.2.23/6591:
#0: ffff88805b065608 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:869 [inline]
#0: ffff88805b065608 (&sb->s_type->i_mutex_key#11){+.+.}-{4:4}, at: __sock_release+0x86/0x270 net/socket.c:646
#1: ffff888058b0a4d8 (sk_lock-AF_SMC/1){+.+.}-{0:0}, at: smc_release+0x378/0x5f0 net/smc/af_smc.c:341
#2: ffff88805b878fd8 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1667 [inline]
#2: ffff88805b878fd8 (k-sk_lock-AF_INET6){+.+.}-{0:0}, at: inet_shutdown+0x67/0x440 net/ipv4/af_inet.c:905
#3: ffff88805b87aa58 (k-slock-AF_INET6){+.-.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
#3: ffff88805b87aa58 (k-slock-AF_INET6){+.-.}-{3:3}, at: inet_csk_listen_stop+0x203/0x1090 net/ipv4/inet_connection_sock.c:1495

stack backtrace:
CPU: 0 UID: 0 PID: 6591 Comm: syz.2.23 Not tainted 6.16.0-rc3-syzkaller-gdfba48a70cb6-dirty #0 PREEMPT(full)

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025

RIP: 0033:0x7fec9fd7e719

Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48

RSP: 002b:00007fec9effe038 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007fec9ff35f80 RCX: 00007fec9fd7e719

RDX: 0000000000000000 RSI: ffffffffffffffff RDI: 0000000000000003

RBP: 00007fec9fdf132e R08: 0000000000000000 R09: 0000000000000000

R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000

R13: 0000000000000000 R14: 00007fec9ff35f80 R15: 00007ffd574ead88

</TASK>


Tested on:

commit: dfba48a7 Merge tag 'i2c-for-6.16-rc4' of git://git.ker..
git tree: upstream

console output: https://syzkaller.appspot.com/x/log.txt?x=11cd688c580000

kernel config: https://syzkaller.appspot.com/x/.config?x=d3e0d55231e0c89c
dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=10e2a982580000

[Hillf Danton]

> Date: Mon, 31 Mar 2025 13:23:20 -0700

> syzbot found the following issue on:
>
> HEAD commit: 850925a8133c Merge tag '9p-for-6.12-rc5' of https://github..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1227aa87980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=17c0d505695d6b0
> dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15489230580000

#syz test upstream master

--- x/net/smc/af_smc.c
+++ y/net/smc/af_smc.c

@@ -127,6 +127,8 @@ static struct sock *smc_tcp_syn_recv_soc

struct sock *child;

smc = smc_clcsock_user_data(sk);
+ if (!smc)
+ goto drop;

if (READ_ONCE(sk->sk_ack_backlog) + atomic_read(&smc->queued_smc_hs) >
sk->sk_max_ack_backlog)

--

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-by: syzbot+827ae2...@syzkaller.appspotmail.com
Tested-by: syzbot+827ae2...@syzkaller.appspotmail.com

Tested on:

commit: d0b3b7b2 Linux 6.16-rc4
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11da6982580000
kernel config: https://syzkaller.appspot.com/x/.config?x=31697df50f24445

dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=15b963d4580000

Note: testing is done by a robot and is best-effort only.

[Paolo Abeni]

Please stop cc-ing netdev and other kernel ML with this tests. You
should keep just the syzkaller related MLs and a very restricted list of
individuals (i.e. no maintainers).

Thanks,

Paolo

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: db9030a787e3 Merge remote-tracking branch 'will/for-next/p..
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=167bc97c580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fdc83aa8a8b9d1ae
dashboard link: https://syzkaller.appspot.com/bug?extid=827ae2bfb3a3529333e9
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10496884580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14da2692580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8932d8648ef5/disk-db9030a7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/8446b6e4ef5c/vmlinux-db9030a7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b17118b94e44/Image-db9030a7.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+827ae2...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: null-ptr-deref in instrument_atomic_read include/linux/instrumented.h:68 [inline]
BUG: KASAN: null-ptr-deref in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]

BUG: KASAN: null-ptr-deref in smc_tcp_syn_recv_sock+0x84/0x574 net/smc/af_smc.c:134
Read of size 4 at addr 0000000000000acc by task syz.0.42/6792

CPU: 1 UID: 0 PID: 6792 Comm: syz.0.42 Not tainted syzkaller #0 PREEMPT
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
Call trace:
show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
__dump_stack+0x30/0x40 lib/dump_stack.c:94
dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
print_report+0x58/0x84 mm/kasan/report.c:485
kasan_report+0xb0/0x110 mm/kasan/report.c:595
check_region_inline mm/kasan/generic.c:-1 [inline]
kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:200
__kasan_check_read+0x20/0x30 mm/kasan/shadow.c:31

instrument_atomic_read include/linux/instrumented.h:68 [inline]
atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]

smc_tcp_syn_recv_sock+0x84/0x574 net/smc/af_smc.c:134
tcp_check_req+0xf6c/0x18e8 net/ipv4/tcp_minisocks.c:912
tcp_v6_rcv+0xf50/0x2460 net/ipv6/tcp_ipv6.c:1845
ip6_protocol_deliver_rcu+0x9a4/0x12d4 net/ipv6/ip6_input.c:438
ip6_input_finish+0x154/0x350 net/ipv6/ip6_input.c:489
NF_HOOK+0x2c4/0x358 include/linux/netfilter.h:318
ip6_input+0x15c/0x270 net/ipv6/ip6_input.c:500
dst_input include/net/dst.h:474 [inline]
ip6_rcv_finish+0x1f0/0x21c net/ipv6/ip6_input.c:79
NF_HOOK+0x2c4/0x358 include/linux/netfilter.h:318
ipv6_rcv+0x9c/0xbc net/ipv6/ip6_input.c:311
__netif_receive_skb_one_core net/core/dev.c:6079 [inline]
__netif_receive_skb+0xcc/0x2a8 net/core/dev.c:6192
process_backlog+0x60c/0x10e4 net/core/dev.c:6544
__napi_poll+0xb4/0x310 net/core/dev.c:7594
napi_poll net/core/dev.c:7657 [inline]
net_rx_action+0x548/0xd00 net/core/dev.c:7784
handle_softirqs+0x328/0xc88 kernel/softirq.c:622
__do_softirq+0x14/0x20 kernel/softirq.c:656
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:68
call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:891
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:73
do_softirq+0x90/0xf8 kernel/softirq.c:523
__local_bh_enable_ip+0x240/0x35c kernel/softirq.c:450
local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33
rcu_read_unlock_bh include/linux/rcupdate.h:936 [inline]
__dev_queue_xmit+0x17ac/0x32a8 net/core/dev.c:4790
dev_queue_xmit include/linux/netdevice.h:3365 [inline]
neigh_hh_output include/net/neighbour.h:531 [inline]
neigh_output include/net/neighbour.h:545 [inline]
ip6_finish_output2+0x1150/0x1a78 net/ipv6/ip6_output.c:136
__ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
ip6_finish_output+0x418/0x7b4 net/ipv6/ip6_output.c:220
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x2c8/0x640 net/ipv6/ip6_output.c:247
dst_output include/net/dst.h:464 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
ip6_xmit+0x1134/0x1a20 net/ipv6/ip6_output.c:371
inet6_csk_xmit+0x454/0x66c net/ipv6/inet6_connection_sock.c:120
__tcp_transmit_skb+0x1a34/0x3214 net/ipv4/tcp_output.c:1628
tcp_transmit_skb net/ipv4/tcp_output.c:1646 [inline]
tcp_write_xmit+0x159c/0x52a4 net/ipv4/tcp_output.c:2999
__tcp_push_pending_frames net/ipv4/tcp_output.c:3182 [inline]
tcp_send_fin+0x620/0xc08 net/ipv4/tcp_output.c:3800
__tcp_close+0x558/0xf68 net/ipv4/tcp.c:3207
tcp_close+0x38/0x144 net/ipv4/tcp.c:3298
inet_release+0x154/0x1d0 net/ipv4/af_inet.c:437
inet6_release+0x5c/0x78 net/ipv6/af_inet6.c:487
__sock_release net/socket.c:662 [inline]
sock_close+0xa0/0x1e4 net/socket.c:1455
__fput+0x340/0x75c fs/file_table.c:468
____fput+0x20/0x58 fs/file_table.c:496
task_work_run+0x1dc/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xfc/0x178 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:81 [inline]
el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:725
el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
==================================================================
Unable to handle kernel paging request at virtual address dfff800000000159
KASAN: null-ptr-deref in range [0x0000000000000ac8-0x0000000000000acf]
Mem abort info:
ESR = 0x0000000096000005
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x05: level 1 translation fault
Data abort info:
ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[dfff800000000159] address between user and kernel address ranges
Internal error: Oops: 0000000096000005 [#1] SMP
Modules linked in:
CPU: 1 UID: 0 PID: 6792 Comm: syz.0.42 Tainted: G B syzkaller #0 PREEMPT
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/03/2025
pstate: 43400005 (nZcv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline]
pc : atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline]
pc : smc_tcp_syn_recv_sock+0x88/0x574 net/smc/af_smc.c:134
lr : instrument_atomic_read include/linux/instrumented.h:68 [inline]
lr : atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline]
lr : smc_tcp_syn_recv_sock+0x84/0x574 net/smc/af_smc.c:134
sp : ffff800097937340
x29: ffff800097937340 x28: 0000000000000000 x27: dfff800000000000
x26: 0000000000000000 x25: 0000000000000acc x24: ffff0000cdd47270
x23: ffff0000d72a7a00 x22: ffff0000d72a7a00 x21: ffff800097937480
x20: 0000000000000000 x19: ffff0000c7c80000 x18: 0000000000000000
x17: 3d3d3d3d3d3d3d3d x16: ffff800082debe40 x15: 0000000000000001
x14: 1ffff000125cd314 x13: 0000000000000000 x12: 0000000000000000
x11: ffff7000125cd315 x10: 0000000000ff0100 x9 : 0000000000000000
x8 : 0000000000000159 x7 : 0000000000000001 x6 : ffff8000805653c0
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000803c084c
x2 : 0000000000000001 x1 : 0000000000000000 x0 : 0000000000000000
Call trace:
raw_atomic_read include/linux/atomic/atomic-arch-fallback.h:457 [inline] (P)
atomic_read include/linux/atomic/atomic-instrumented.h:33 [inline] (P)
smc_tcp_syn_recv_sock+0x88/0x574 net/smc/af_smc.c:134 (P)
tcp_check_req+0xf6c/0x18e8 net/ipv4/tcp_minisocks.c:912
tcp_v6_rcv+0xf50/0x2460 net/ipv6/tcp_ipv6.c:1845
ip6_protocol_deliver_rcu+0x9a4/0x12d4 net/ipv6/ip6_input.c:438
ip6_input_finish+0x154/0x350 net/ipv6/ip6_input.c:489
NF_HOOK+0x2c4/0x358 include/linux/netfilter.h:318
ip6_input+0x15c/0x270 net/ipv6/ip6_input.c:500
dst_input include/net/dst.h:474 [inline]
ip6_rcv_finish+0x1f0/0x21c net/ipv6/ip6_input.c:79
NF_HOOK+0x2c4/0x358 include/linux/netfilter.h:318
ipv6_rcv+0x9c/0xbc net/ipv6/ip6_input.c:311
__netif_receive_skb_one_core net/core/dev.c:6079 [inline]
__netif_receive_skb+0xcc/0x2a8 net/core/dev.c:6192
process_backlog+0x60c/0x10e4 net/core/dev.c:6544
__napi_poll+0xb4/0x310 net/core/dev.c:7594
napi_poll net/core/dev.c:7657 [inline]
net_rx_action+0x548/0xd00 net/core/dev.c:7784
handle_softirqs+0x328/0xc88 kernel/softirq.c:622
__do_softirq+0x14/0x20 kernel/softirq.c:656
____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:68
call_on_irq_stack+0x30/0x48 arch/arm64/kernel/entry.S:891
do_softirq_own_stack+0x20/0x2c arch/arm64/kernel/irq.c:73
do_softirq+0x90/0xf8 kernel/softirq.c:523
__local_bh_enable_ip+0x240/0x35c kernel/softirq.c:450
local_bh_enable+0x28/0x34 include/linux/bottom_half.h:33
rcu_read_unlock_bh include/linux/rcupdate.h:936 [inline]
__dev_queue_xmit+0x17ac/0x32a8 net/core/dev.c:4790
dev_queue_xmit include/linux/netdevice.h:3365 [inline]
neigh_hh_output include/net/neighbour.h:531 [inline]
neigh_output include/net/neighbour.h:545 [inline]
ip6_finish_output2+0x1150/0x1a78 net/ipv6/ip6_output.c:136
__ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]
ip6_finish_output+0x418/0x7b4 net/ipv6/ip6_output.c:220
NF_HOOK_COND include/linux/netfilter.h:307 [inline]
ip6_output+0x2c8/0x640 net/ipv6/ip6_output.c:247
dst_output include/net/dst.h:464 [inline]
NF_HOOK include/linux/netfilter.h:318 [inline]
ip6_xmit+0x1134/0x1a20 net/ipv6/ip6_output.c:371
inet6_csk_xmit+0x454/0x66c net/ipv6/inet6_connection_sock.c:120
__tcp_transmit_skb+0x1a34/0x3214 net/ipv4/tcp_output.c:1628
tcp_transmit_skb net/ipv4/tcp_output.c:1646 [inline]
tcp_write_xmit+0x159c/0x52a4 net/ipv4/tcp_output.c:2999
__tcp_push_pending_frames net/ipv4/tcp_output.c:3182 [inline]
tcp_send_fin+0x620/0xc08 net/ipv4/tcp_output.c:3800
__tcp_close+0x558/0xf68 net/ipv4/tcp.c:3207
tcp_close+0x38/0x144 net/ipv4/tcp.c:3298
inet_release+0x154/0x1d0 net/ipv4/af_inet.c:437
inet6_release+0x5c/0x78 net/ipv6/af_inet6.c:487
__sock_release net/socket.c:662 [inline]
sock_close+0xa0/0x1e4 net/socket.c:1455
__fput+0x340/0x75c fs/file_table.c:468
____fput+0x20/0x58 fs/file_table.c:496
task_work_run+0x1dc/0x260 kernel/task_work.c:227
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop+0xfc/0x178 kernel/entry/common.c:43
exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
arm64_exit_to_user_mode arch/arm64/kernel/entry-common.c:81 [inline]
el0_svc+0x170/0x254 arch/arm64/kernel/entry-common.c:725
el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:743
el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596
Code: 52800081 aa1903e0 9761d4da d343ff28 (38fb6908)

---[ end trace 0000000000000000 ]---

----------------
Code disassembly (best guess):
0: 52800081 mov w1, #0x4 // #4
4: aa1903e0 mov x0, x25
8: 9761d4da bl 0xfffffffffd875370
c: d343ff28 lsr x8, x25, #3
* 10: 38fb6908 ldrsb w8, [x8, x27] <-- trapping instruction


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