general protection fault in llc_ui_sendmsg

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 74766a973637 Linux 4.14.275
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=16e728a0f00000
kernel config: https://syzkaller.appspot.com/x/.config?x=78767ee43940f0a8
dashboard link: https://syzkaller.appspot.com/bug?extid=b49f140c84fa2c6f6deb
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+b49f14...@syzkaller.appspotmail.com

sock_ioctl+0x254/0x4c0 net/socket.c:1038
vfs_ioctl fs/ioctl.c:46 [inline]
file_ioctl fs/ioctl.c:500 [inline]
do_vfs_ioctl+0x75a/0xff0 fs/ioctl.c:684
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
CPU: 1 PID: 10012 Comm: syz-executor.5 Not tainted 4.14.275-syzkaller #0
RIP: 0033:0x7fc36ad42049
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RSP: 002b:00007fc3696b7168 EFLAGS: 00000246
task: ffff88808dc2a500 task.stack: ffff88809b860000
ORIG_RAX: 0000000000000010
RIP: 0010:dev_put include/linux/netdevice.h:3381 [inline]
RIP: 0010:llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320
RAX: ffffffffffffffda RBX: 00007fc36ae54f60 RCX: 00007fc36ad42049
RSP: 0018:ffff88809b867970 EFLAGS: 00010202
RDX: 0000000020000140 RSI: 0000000000008940 RDI: 0000000000000003
RBP: 00007fc3696b71d0 R08: 0000000000000000 R09: 0000000000000000
RAX: dffffc0000000000 RBX: ffff88809f155400 RCX: ffffc90005cc2000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
RDX: 00000000000000a8 RSI: ffffffff85d0c563 RDI: 0000000000000540
R13: 00007ffdb16c853f R14: 00007fc3696b7300 R15: 0000000000022000
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 00000000ffffffea
R13: ffff88809b867c10 R14: ffff88807b53aac0 R15: ffff88807b53aae0
FS: 00007f0e328b7700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f9d900b2008 CR3: 000000009f26a000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
llc_ui_sendmsg+0x638/0xec0 net/llc/af_llc.c:952
sock_sendmsg_nosec net/socket.c:646 [inline]
sock_sendmsg+0xb5/0x100 net/socket.c:656
___sys_sendmsg+0x326/0x800 net/socket.c:2062
__sys_sendmmsg+0x129/0x330 net/socket.c:2152
SYSC_sendmmsg net/socket.c:2183 [inline]
SyS_sendmmsg+0x2f/0x50 net/socket.c:2178
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7f0e33f42049
RSP: 002b:00007f0e328b7168 EFLAGS: 00000246 ORIG_RAX: 0000000000000133
RAX: ffffffffffffffda RBX: 00007f0e34054f60 RCX: 00007f0e33f42049
RDX: 0000000000000005 RSI: 0000000020001040 RDI: 0000000000000004
RBP: 00007f0e33f9c08d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000004 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff44b2353f R14: 00007f0e328b7300 R15: 0000000000022000
Code: 55 ff ff 48 0f ba 73 60 08 45 31 e4 31 ed e8 dd 7c 84 fb 48 8d bd 40 05 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f2 00 00 00 48 8b 85 40 05 00 00 65 ff 08 44
RIP: dev_put include/linux/netdevice.h:3381 [inline] RSP: ffff88809b867970
RIP: llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320 RSP: ffff88809b867970
---[ end trace eaebd884e17caab3 ]---
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 48 0f decl 0xf(%rax)
3: ba 73 60 08 45 mov $0x45086073,%edx
8: 31 e4 xor %esp,%esp
a: 31 ed xor %ebp,%ebp
c: e8 dd 7c 84 fb callq 0xfb847cee
11: 48 8d bd 40 05 00 00 lea 0x540(%rbp),%rdi
18: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1f: fc ff df
22: 48 89 fa mov %rdi,%rdx
25: 48 c1 ea 03 shr $0x3,%rdx
* 29: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2d: 0f 85 f2 00 00 00 jne 0x125
33: 48 8b 85 40 05 00 00 mov 0x540(%rbp),%rax
3a: 65 ff 08 decl %gs:(%rax)
3d: 44 rex.R


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[syzbot]

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