[syzbot] [serial?] general protection fault in n_tty_receive_buf_common (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 786c8248dbd3 Merge tag 'perf-tools-fixes-for-v6.11-2024-07..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17f0d29d980000
kernel config: https://syzkaller.appspot.com/x/.config?x=47beaba1a1054668
dashboard link: https://syzkaller.appspot.com/bug?extid=2dda672e146ff12ccb02
compiler: gcc (Debian 12.2.0-14) 12.2.0, 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/e4bf4a8f547d/disk-786c8248.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9b69a5fd8929/vmlinux-786c8248.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e0060dfb7885/bzImage-786c8248.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2dda67...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000044c: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: probably user-memory-access in range [0x0000000000002260-0x0000000000002267]
CPU: 1 UID: 0 PID: 12 Comm: kworker/u8:1 Not tainted 6.10.0-syzkaller-12246-g786c8248dbd3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Workqueue: events_unbound flush_to_ldisc
RIP: 0010:n_tty_receive_buf_common+0xf3/0x1980 drivers/tty/n_tty.c:1718
Code: 00 48 89 74 24 60 4a 8d 0c 39 4a 8d 34 3a 48 89 4c 24 70 48 89 74 24 68 48 89 84 24 a0 00 00 00 e8 b2 c7 95 fc 48 8b 44 24 68 <80> 38 00 0f 85 af 15 00 00 48 8b 44 24 18 48 8b a8 60 22 00 00 48
RSP: 0018:ffffc90000117ad0 EFLAGS: 00010293
RAX: dffffc000000044c RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffff8880172fda00 RSI: ffffffff84f4beee RDI: 000000000000005c
RBP: 0000000000000004 R08: 0000000000000001 R09: ffffed100bfcec50
R10: ffff88805fe76287 R11: 0000000000000000 R12: ffffffff84f4d790
R13: 0000000000000000 R14: ffff88805fe76000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f62429bcfc8 CR3: 0000000066f7a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tty_ldisc_receive_buf+0xa2/0x190 drivers/tty/tty_buffer.c:387
tty_port_default_receive_buf+0x70/0xb0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:445 [inline]
flush_to_ldisc+0x264/0x780 drivers/tty/tty_buffer.c:495
process_one_work+0x9c5/0x1b40 kernel/workqueue.c:3231
process_scheduled_works kernel/workqueue.c:3312 [inline]
worker_thread+0x6c8/0xf20 kernel/workqueue.c:3390
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:n_tty_receive_buf_common+0xf3/0x1980 drivers/tty/n_tty.c:1718
Code: 00 48 89 74 24 60 4a 8d 0c 39 4a 8d 34 3a 48 89 4c 24 70 48 89 74 24 68 48 89 84 24 a0 00 00 00 e8 b2 c7 95 fc 48 8b 44 24 68 <80> 38 00 0f 85 af 15 00 00 48 8b 44 24 18 48 8b a8 60 22 00 00 48
RSP: 0018:ffffc90000117ad0 EFLAGS: 00010293
RAX: dffffc000000044c RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffff8880172fda00 RSI: ffffffff84f4beee RDI: 000000000000005c
RBP: 0000000000000004 R08: 0000000000000001 R09: ffffed100bfcec50
R10: ffff88805fe76287 R11: 0000000000000000 R12: ffffffff84f4d790
R13: 0000000000000000 R14: ffff88805fe76000 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880b9300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055557bdc65c8 CR3: 0000000058bdc000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 48 89 74 24 60 mov %rsi,0x60(%rsp)
5: 4a 8d 0c 39 lea (%rcx,%r15,1),%rcx
9: 4a 8d 34 3a lea (%rdx,%r15,1),%rsi
d: 48 89 4c 24 70 mov %rcx,0x70(%rsp)
12: 48 89 74 24 68 mov %rsi,0x68(%rsp)
17: 48 89 84 24 a0 00 00 mov %rax,0xa0(%rsp)
1e: 00
1f: e8 b2 c7 95 fc call 0xfc95c7d6
24: 48 8b 44 24 68 mov 0x68(%rsp),%rax
* 29: 80 38 00 cmpb $0x0,(%rax) <-- trapping instruction
2c: 0f 85 af 15 00 00 jne 0x15e1
32: 48 8b 44 24 18 mov 0x18(%rsp),%rax
37: 48 8b a8 60 22 00 00 mov 0x2260(%rax),%rbp
3e: 48 rex.W


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