[v6.1] general protection fault in dccp_write_xmit

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e7cddbb41b63 Linux 6.1.67
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1716893ae80000
kernel config: https://syzkaller.appspot.com/x/.config?x=8160fc00d26f042b
dashboard link: https://syzkaller.appspot.com/bug?extid=2ff34c2e902e489b4d8c
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/8956c6179c51/disk-e7cddbb4.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d5ebbb26ed14/vmlinux-e7cddbb4.xz
kernel image: https://storage.googleapis.com/syzbot-assets/30e370b152f6/bzImage-e7cddbb4.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ff34c...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 19384 Comm: syz-executor.1 Not tainted 6.1.67-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
RIP: 0010:dccp_write_xmit+0x6b/0x220 net/dccp/output.c:356
Code: 03 48 89 44 24 08 4c 89 2c 24 48 8b 44 24 08 80 3c 28 00 74 08 48 89 df e8 72 b9 16 f8 49 89 df 48 8b 1b 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 57 b9 16 f8 48 8b 1b b8 b0 00 00 00
RSP: 0018:ffffc900054e7a18 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807e591280
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888040873340
RBP: dffffc0000000000 R08: ffffffff89cc2b3d R09: fffffbfff2091e5c
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff88807e591280
R13: ffff888040873340 R14: 0000000000000105 R15: ffff888040873c30
FS: 00007f02314776c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f0226e30000 CR3: 0000000021ad3000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
dccp_sendmsg+0x767/0xbd0 net/dccp/proto.c:798
sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]
sock_write_iter+0x394/0x4e0 net/socket.c:1130
call_write_iter include/linux/fs.h:2248 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x7ae/0xba0 fs/read_write.c:584
ksys_write+0x19c/0x2c0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f023067cba9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f02314770c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f023079c050 RCX: 00007f023067cba9
RDX: 0000000000000105 RSI: 0000000020000000 RDI: 0000000000000003
RBP: 00007f02306c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f023079c050 R15: 00007ffeb88c3288
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
RIP: 0010:dccp_write_xmit+0x6b/0x220 net/dccp/output.c:356
Code: 03 48 89 44 24 08 4c 89 2c 24 48 8b 44 24 08 80 3c 28 00 74 08 48 89 df e8 72 b9 16 f8 49 89 df 48 8b 1b 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 57 b9 16 f8 48 8b 1b b8 b0 00 00 00
RSP: 0018:ffffc900054e7a18 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88807e591280
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff888040873340
RBP: dffffc0000000000 R08: ffffffff89cc2b3d R09: fffffbfff2091e5c
R10: 0000000000000000 R11: dffffc0000000001 R12: ffff88807e591280
R13: ffff888040873340 R14: 0000000000000105 R15: ffff888040873c30
FS: 00007f02314776c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f2d8339d988 CR3: 0000000021ad3000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 03 48 89 add -0x77(%rax),%ecx
3: 44 24 08 rex.R and $0x8,%al
6: 4c 89 2c 24 mov %r13,(%rsp)
a: 48 8b 44 24 08 mov 0x8(%rsp),%rax
f: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1)
13: 74 08 je 0x1d
15: 48 89 df mov %rbx,%rdi
18: e8 72 b9 16 f8 call 0xf816b98f
1d: 49 89 df mov %rbx,%r15
20: 48 8b 1b mov (%rbx),%rbx
23: 48 89 d8 mov %rbx,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 28 00 cmpb $0x0,(%rax,%rbp,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 48 89 df mov %rbx,%rdi
33: e8 57 b9 16 f8 call 0xf816b98f
38: 48 8b 1b mov (%rbx),%rbx
3b: b8 b0 00 00 00 mov $0xb0,%eax


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: 4aa6747d9352 Linux 6.1.69
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13a31bd6e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e3efadc69a1b0490

dashboard link: https://syzkaller.appspot.com/bug?extid=2ff34c2e902e489b4d8c
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d0e9cee80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15a92f76e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/31c5d5a5223e/disk-4aa6747d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/85c4938c28c7/vmlinux-4aa6747d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0fcb53eb57be/Image-4aa6747d.gz.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ff34c...@syzkaller.appspotmail.com

Unable to handle kernel paging request at virtual address dfff800000000000

KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]

Mem abort info:
ESR = 0x0000000096000006
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000006
CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 18236 Comm: syz-executor346 Not tainted 6.1.69-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023

pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
pc : dccp_write_xmit+0x6c/0x208 net/dccp/output.c:356
lr : dccp_write_xmit+0x30/0x208 net/dccp/output.c:355
sp : ffff8000250f74c0
x29: ffff8000250f74c0
x28: ffff700004a1eeac
x27: 00000000000f0000

x26: 1fffe0001b04eca6
x25: dfff800000000000
x24: 0000000000000000

x23: 0000000000000000 x22: ffff0000d3088dc0 x21: ffff800017fdf490
x20: ffff0000d8276530 x19: ffff0000d8275c40 x18: ffff8000250f7160
x17: ffff8000188a7000 x16: ffff8000084fa434 x15: ffff80001838cf80
x14: 0000000075644433
x13: dfff800000000000
x12: 0000000000000003
x11: 0000000000ff0100 x10: 0000000000000000 x9 : 1fffe0001b04ebd9
x8 : 0000000000000000
x7 : 0000000000000000 x6 : 0000000000000000

x5 : ffff800018a21c28
x4 : 0000000000000008 x3 : 0000000000000000

x2 : 0000000000000006
x1 : 0000000000000000
x0 : ffff0000d3088dc0
Call trace:
ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline]
dccp_write_xmit+0x6c/0x208 net/dccp/output.c:356
dccp_sendmsg+0x634/0xb80 net/dccp/proto.c:798
inet_sendmsg+0x15c/0x290 net/ipv4/af_inet.c:836

sock_sendmsg_nosec net/socket.c:716 [inline]
__sock_sendmsg net/socket.c:728 [inline]

____sys_sendmsg+0x558/0x844 net/socket.c:2499
___sys_sendmsg net/socket.c:2553 [inline]
__sys_sendmmsg+0x318/0x7d8 net/socket.c:2639
__do_sys_sendmmsg net/socket.c:2668 [inline]
__se_sys_sendmmsg net/socket.c:2665 [inline]
__arm64_sys_sendmmsg+0xa0/0xbc net/socket.c:2665
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: aa1403e0 97a22f85 f9400297 d343fee8 (38796908)

---[ end trace 0000000000000000 ]---

----------------
Code disassembly (best guess):

0: aa1403e0 mov x0, x20
4: 97a22f85 bl 0xfffffffffe88be18
8: f9400297 ldr x23, [x20]
c: d343fee8 lsr x8, x23, #3
* 10: 38796908 ldrb w8, [x8, x25] <-- trapping instruction


---
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