[syzbot] BUG: unable to handle kernel paging request in atm_tc_destroy

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 0b34d68049b0 net: enable usercopy for skb_small_head_cache
git tree: net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14cb251f480000
kernel config: https://syzkaller.appspot.com/x/.config?x=bd3e305b3a7ab2b0
dashboard link: https://syzkaller.appspot.com/bug?extid=d44d88f1d11e6ca8576b
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1259c7cb480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1789967d480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e6e9cd443f49/disk-0b34d680.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1d27805ca50d/vmlinux-0b34d680.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0a3e607b6ca7/bzImage-0b34d680.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d44d88...@syzkaller.appspotmail.com

BUG: unable to handle page fault for address: ffffffffffffffa0
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD c48f067 P4D c48f067 PUD c491067 PMD 0
Oops: 0000 [#1] PREEMPT SMP KASAN
CPU: 1 PID: 5075 Comm: syz-executor134 Not tainted 6.2.0-rc6-syzkaller-01486-g0b34d68049b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/21/2023
RIP: 0010:atm_tc_destroy+0x7d/0x250 net/sched/sch_atm.c:588
Code: 0f 84 52 01 00 00 48 bd 00 00 00 00 00 fc ff df e8 88 0e 8b f9 4c 8d 73 28 4c 89 f0 48 c1 e8 03 80 3c 28 00 0f 85 70 01 00 00 <48> 8b 7b 28 e8 ea f4 f2 ff 4c 89 f0 48 c1 e8 03 80 3c 28 00 0f 85
RSP: 0018:ffffc90003c0f3f0 EFLAGS: 00010246
RAX: 1ffffffffffffff4 RBX: ffffffffffffff78 RCX: 0000000000000000
RDX: ffff88802695d7c0 RSI: ffffffff87f5ed08 RDI: ffff888022026000
RBP: dffffc0000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: ffffffffffffffea R11: 0000000000000000 R12: ffff888022026370
R13: ffff888022026000 R14: ffffffffffffffa0 R15: ffff888021d6c000
FS: 0000555555aee300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffa0 CR3: 000000001c561000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
qdisc_create+0xaca/0x1150 net/sched/sch_api.c:1329
tc_modify_qdisc+0x948/0x19c0 net/sched/sch_api.c:1662
rtnetlink_rcv_msg+0x43e/0xca0 net/core/rtnetlink.c:6174
netlink_rcv_skb+0x165/0x440 net/netlink/af_netlink.c:2574
netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
netlink_unicast+0x547/0x7f0 net/netlink/af_netlink.c:1365
netlink_sendmsg+0x91b/0xe10 net/netlink/af_netlink.c:1942
sock_sendmsg_nosec net/socket.c:722 [inline]
sock_sendmsg+0xde/0x190 net/socket.c:745
____sys_sendmsg+0x71c/0x900 net/socket.c:2501
___sys_sendmsg+0x110/0x1b0 net/socket.c:2555
__sys_sendmsg+0xf7/0x1c0 net/socket.c:2584
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6162cddba9
Code: 28 c3 e8 1a 15 00 00 66 2e 0f 1f 84 00 00 00 00 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 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe242b7018 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00007f6162d4bed0 RCX: 00007f6162cddba9
RDX: 0000000000000000 RSI: 00000000200001c0 RDI: 0000000000000003
RBP: 00007ffe242b7028 R08: 00007f6162d4be40 R09: 00007f6162d4be40
R10: 00007f6162d4be40 R11: 0000000000000246 R12: 00007ffe242b7030
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
CR2: ffffffffffffffa0
---[ end trace 0000000000000000 ]---
RIP: 0010:atm_tc_destroy+0x7d/0x250 net/sched/sch_atm.c:588
Code: 0f 84 52 01 00 00 48 bd 00 00 00 00 00 fc ff df e8 88 0e 8b f9 4c 8d 73 28 4c 89 f0 48 c1 e8 03 80 3c 28 00 0f 85 70 01 00 00 <48> 8b 7b 28 e8 ea f4 f2 ff 4c 89 f0 48 c1 e8 03 80 3c 28 00 0f 85
RSP: 0018:ffffc90003c0f3f0 EFLAGS: 00010246
RAX: 1ffffffffffffff4 RBX: ffffffffffffff78 RCX: 0000000000000000
RDX: ffff88802695d7c0 RSI: ffffffff87f5ed08 RDI: ffff888022026000
RBP: dffffc0000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: ffffffffffffffea R11: 0000000000000000 R12: ffff888022026370
R13: ffff888022026000 R14: ffffffffffffffa0 R15: ffff888021d6c000
FS: 0000555555aee300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffa0 CR3: 000000001c561000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 0f 84 52 01 00 00 je 0x158
6: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp
d: fc ff df
10: e8 88 0e 8b f9 callq 0xf98b0e9d
15: 4c 8d 73 28 lea 0x28(%rbx),%r14
19: 4c 89 f0 mov %r14,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
24: 0f 85 70 01 00 00 jne 0x19a
* 2a: 48 8b 7b 28 mov 0x28(%rbx),%rdi <-- trapping instruction
2e: e8 ea f4 f2 ff callq 0xfff2f51d
33: 4c 89 f0 mov %r14,%rax
36: 48 c1 e8 03 shr $0x3,%rax
3a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
3e: 0f .byte 0xf
3f: 85 .byte 0x85


---
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[Eric Dumazet]

Fix would be :

https://patchwork.kernel.org/project/netdevbpf/patch/20230210152605.1...@google.com/