[moderation] [net?] general protection fault in slip_receive_buf

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 18b44bc5a672 ovl: Always reevaluate the file signature for..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=171c51d9a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=c7b1aac4a6659b6d
dashboard link: https://syzkaller.appspot.com/bug?extid=d287c0c38d54942a4e3c
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [da...@davemloft.net edum...@google.com ku...@kernel.org linux-...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/037fe80d01eb/disk-18b44bc5.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c93c08cecdf2/vmlinux-18b44bc5.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cce5b987d985/bzImage-18b44bc5.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d287c0...@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: 0 PID: 57 Comm: kworker/u4:4 Not tainted 6.5.0-rc3-syzkaller-00024-g18b44bc5a672 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2023
Workqueue: events_unbound flush_to_ldisc
RIP: 0010:slip_unesc drivers/net/slip/slip.c:987 [inline]
RIP: 0010:slip_receive_buf+0x412/0xbe0 drivers/net/slip/slip.c:709
Code: 02 00 0f 85 a0 07 00 00 41 8d 47 01 4c 03 bb b0 00 00 00 89 83 b8 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <0f> b6 04 02 4c 89 fa 83 e2 07 38 d0 7f 0c 84 c0 74 08 4c 89 ff e8
RSP: 0018:ffffc90001587b88 EFLAGS: 00010256
RAX: dffffc0000000000 RBX: ffff88803b92cc80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff85d225be RDI: ffff88803b92cd30
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000480 R11: 000000000000004e R12: dffffc0000000000
R13: ffff88803b92cd68 R14: ffff8880385c916a R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020006000 CR3: 000000002af04000 CR4: 0000000000350ef0
Call Trace:
<TASK>
tty_ldisc_receive_buf+0x143/0x180 drivers/tty/tty_buffer.c:461
tty_port_default_receive_buf+0x6f/0xa0 drivers/tty/tty_port.c:39
receive_buf drivers/tty/tty_buffer.c:515 [inline]
flush_to_ldisc+0x252/0x7c0 drivers/tty/tty_buffer.c:565
process_one_work+0xaa2/0x16f0 kernel/workqueue.c:2597
worker_thread+0x687/0x1110 kernel/workqueue.c:2748
kthread+0x33a/0x430 kernel/kthread.c:389
ret_from_fork+0x2c/0x70 arch/x86/kernel/process.c:145
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:296
RIP: 0000:0x0
Code: Unable to access opcode bytes at 0xffffffffffffffd6.
RSP: 0000:0000000000000000 EFLAGS: 00000000 ORIG_RAX: 0000000000000000
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:slip_unesc drivers/net/slip/slip.c:987 [inline]
RIP: 0010:slip_receive_buf+0x412/0xbe0 drivers/net/slip/slip.c:709
Code: 02 00 0f 85 a0 07 00 00 41 8d 47 01 4c 03 bb b0 00 00 00 89 83 b8 00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 <0f> b6 04 02 4c 89 fa 83 e2 07 38 d0 7f 0c 84 c0 74 08 4c 89 ff e8
RSP: 0018:ffffc90001587b88 EFLAGS: 00010256
RAX: dffffc0000000000 RBX: ffff88803b92cc80 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff85d225be RDI: ffff88803b92cd30
RBP: 0000000000000000 R08: 0000000000000004 R09: 0000000000000000
R10: 0000000000000480 R11: 000000000000004e R12: dffffc0000000000
R13: ffff88803b92cd68 R14: ffff8880385c916a R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9ff0ef7378 CR3: 000000002792f000 CR4: 0000000000350ee0
----------------
Code disassembly (best guess):
0: 02 00 add (%rax),%al
2: 0f 85 a0 07 00 00 jne 0x7a8
8: 41 8d 47 01 lea 0x1(%r15),%eax
c: 4c 03 bb b0 00 00 00 add 0xb0(%rbx),%r15
13: 89 83 b8 00 00 00 mov %eax,0xb8(%rbx)
19: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
20: fc ff df
23: 4c 89 fa mov %r15,%rdx
26: 48 c1 ea 03 shr $0x3,%rdx
* 2a: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2e: 4c 89 fa mov %r15,%rdx
31: 83 e2 07 and $0x7,%edx
34: 38 d0 cmp %dl,%al
36: 7f 0c jg 0x44
38: 84 c0 test %al,%al
3a: 74 08 je 0x44
3c: 4c 89 ff mov %r15,%rdi
3f: e8 .byte 0xe8


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.