[moderation] [net?] general protection fault in slip_receive_buf (2)

Hello,

syzbot found the following issue on:

HEAD commit: 5cdb2c77c4c3 Merge tag 'net-6.15-rc8' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1174f9f4580000
kernel config: https://syzkaller.appspot.com/x/.config?x=9fd1c9848687d742
dashboard link: https://syzkaller.appspot.com/bug?extid=590bbadae11ce2193aa7
compiler: Debian clang version 20.1.6 (++20250514063057+1e4d39e07757-1~exp1~20250514183223.118), Debian LLD 20.1.6
CC: [[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected]]

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-5cdb2c77.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ccb051b67d5/vmlinux-5cdb2c77.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8cacea9c2d43/bzImage-5cdb2c77.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

sl0: compressed packet ignored
sl0: compressed packet ignored
sl0: compressed packet ignored
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 3016 Comm: kworker/u4:12 Not tainted 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Workqueue: events_unbound flush_to_ldisc
RIP: 0010:slip_unesc drivers/net/slip/slip.c:987 [inline]
RIP: 0010:slip_receive_buf+0x807/0xd60 drivers/net/slip/slip.c:709
Code: 4d 8b 6d 00 48 8b 44 24 20 0f b6 04 18 84 c0 0f 85 14 04 00 00 41 8d 44 24 01 48 8b 0c 24 89 01 4d 01 e5 4c 89 e8 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 13 04 00 00 41 88 6d 00 4c 8b 6c 24 08 48
RSP: 0018:ffffc9000d75f968 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff888043676e38
RDX: 0000000000000000 RSI: 0000000000000480 RDI: 0000000000000000
RBP: 000000000000002c R08: ffff888043676e6f R09: 1ffff110086cedcd
R10: dffffc0000000000 R11: ffffed10086cedce R12: 0000000000000000
R13: 0000000000000000 R14: 000000000000050f R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808d6c2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9d75620440 CR3: 0000000041ed7000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
tty_ldisc_receive_buf+0x116/0x160 drivers/tty/tty_buffer.c:391
tty_port_default_receive_buf+0x6e/0xa0 drivers/tty/tty_port.c:37
receive_buf drivers/tty/tty_buffer.c:445 [inline]
flush_to_ldisc+0x2c5/0x810 drivers/tty/tty_buffer.c:495
process_one_work kernel/workqueue.c:3238 [inline]
process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
kthread+0x70e/0x8a0 kernel/kthread.c:464
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:slip_unesc drivers/net/slip/slip.c:987 [inline]
RIP: 0010:slip_receive_buf+0x807/0xd60 drivers/net/slip/slip.c:709
Code: 4d 8b 6d 00 48 8b 44 24 20 0f b6 04 18 84 c0 0f 85 14 04 00 00 41 8d 44 24 01 48 8b 0c 24 89 01 4d 01 e5 4c 89 e8 48 c1 e8 03 <0f> b6 04 18 84 c0 0f 85 13 04 00 00 41 88 6d 00 4c 8b 6c 24 08 48
RSP: 0018:ffffc9000d75f968 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff888043676e38
RDX: 0000000000000000 RSI: 0000000000000480 RDI: 0000000000000000
RBP: 000000000000002c R08: ffff888043676e6f R09: 1ffff110086cedcd
R10: dffffc0000000000 R11: ffffed10086cedce R12: 0000000000000000
R13: 0000000000000000 R14: 000000000000050f R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff88808d6c2000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffc1050a3d8 CR3: 000000003ef24000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 4d 8b 6d 00 mov 0x0(%r13),%r13
4: 48 8b 44 24 20 mov 0x20(%rsp),%rax
9: 0f b6 04 18 movzbl (%rax,%rbx,1),%eax
d: 84 c0 test %al,%al
f: 0f 85 14 04 00 00 jne 0x429
15: 41 8d 44 24 01 lea 0x1(%r12),%eax
1a: 48 8b 0c 24 mov (%rsp),%rcx
1e: 89 01 mov %eax,(%rcx)
20: 4d 01 e5 add %r12,%r13
23: 4c 89 e8 mov %r13,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 0f b6 04 18 movzbl (%rax,%rbx,1),%eax <-- trapping instruction
2e: 84 c0 test %al,%al
30: 0f 85 13 04 00 00 jne 0x449
36: 41 88 6d 00 mov %bpl,0x0(%r13)
3a: 4c 8b 6c 24 08 mov 0x8(%rsp),%r13
3f: 48 rex.W


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