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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 9c69f8884904 Merge tag 'bcachefs-2025-05-08' of git://evil..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17212670580000
kernel config: https://syzkaller.appspot.com/x/.config?x=b39cb28b0a399ed3
dashboard link: https://syzkaller.appspot.com/bug?extid=82d048181b547233d2a9
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
CC: [andrew...@lunn.ch 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 (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-9c69f888.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/94ebcb9405da/vmlinux-9c69f888.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ef46e43d9928/bzImage-9c69f888.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+82d048...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:0 Not tainted 6.15.0-rc5-syzkaller-00136-g9c69f8884904 #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 nsim_fib_event_work
RIP: 0010:nsim_fib6_rt_create drivers/net/netdevsim/fib.c:551 [inline]
RIP: 0010:nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:752 [inline]
RIP: 0010:nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
RIP: 0010:nsim_fib_event drivers/net/netdevsim/fib.c:889 [inline]
RIP: 0010:nsim_fib_event_work+0x183b/0x2e80 drivers/net/netdevsim/fib.c:1493
Code: 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 e6 11 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 2e 48 8d 7d 10 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e cb 11 00 00 49 8d 46 60 8b 6d
RSP: 0018:ffffc900000c7b10 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888028ffef00 RCX: ffff88802a5cbe50
RDX: 0000000000000002 RSI: ffffffff8712a138 RDI: 0000000000000010
RBP: 0000000000000000 R08: ffffffff911325e2 R09: ffff88816cbc1d60
R10: 0000000000000003 R11: 0000000000002bb0 R12: ffff888046f57960
R13: 0000000000000001 R14: ffff888029870800 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880d69e1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000031b50000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000008054 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
process_one_work+0x9cc/0x1b70 kernel/workqueue.c:3238
process_scheduled_works kernel/workqueue.c:3319 [inline]
worker_thread+0x6c8/0xf10 kernel/workqueue.c:3400
kthread+0x3c2/0x780 kernel/kthread.c:464
ret_from_fork+0x45/0x80 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:nsim_fib6_rt_create drivers/net/netdevsim/fib.c:551 [inline]
RIP: 0010:nsim_fib6_rt_insert drivers/net/netdevsim/fib.c:752 [inline]
RIP: 0010:nsim_fib6_event drivers/net/netdevsim/fib.c:856 [inline]
RIP: 0010:nsim_fib_event drivers/net/netdevsim/fib.c:889 [inline]
RIP: 0010:nsim_fib_event_work+0x183b/0x2e80 drivers/net/netdevsim/fib.c:1493
Code: 00 fc ff df 48 c1 ea 03 80 3c 02 00 0f 85 e6 11 00 00 48 b8 00 00 00 00 00 fc ff df 49 8b 2e 48 8d 7d 10 48 89 fa 48 c1 ea 03 <0f> b6 04 02 84 c0 74 08 3c 03 0f 8e cb 11 00 00 49 8d 46 60 8b 6d
RSP: 0018:ffffc900000c7b10 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888028ffef00 RCX: ffff88802a5cbe50
RDX: 0000000000000002 RSI: ffffffff8712a138 RDI: 0000000000000010
RBP: 0000000000000000 R08: ffffffff911325e2 R09: ffff88816cbc1d60
R10: 0000000000000003 R11: 0000000000002bb0 R12: ffff888046f57960
R13: 0000000000000001 R14: ffff888029870800 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880d69e1000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000000 CR3: 0000000028f0e000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000008054 DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 4 bytes skipped:
0: 48 c1 ea 03 shr $0x3,%rdx
4: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1)
8: 0f 85 e6 11 00 00 jne 0x11f4
e: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
15: fc ff df
18: 49 8b 2e mov (%r14),%rbp
1b: 48 8d 7d 10 lea 0x10(%rbp),%rdi
1f: 48 89 fa mov %rdi,%rdx
22: 48 c1 ea 03 shr $0x3,%rdx
* 26: 0f b6 04 02 movzbl (%rdx,%rax,1),%eax <-- trapping instruction
2a: 84 c0 test %al,%al
2c: 74 08 je 0x36
2e: 3c 03 cmp $0x3,%al
30: 0f 8e cb 11 00 00 jle 0x1201
36: 49 8d 46 60 lea 0x60(%r14),%rax
3a: 8b .byte 0x8b
3b: 6d insl (%dx),%es:(%rdi)


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[syzbot]

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