general protection fault in ax25_send_frame

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: fa5941f4 Linux 4.14.114
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1599a0e0a00000
kernel config: https://syzkaller.appspot.com/x/.config?x=d7780000df8e070e
dashboard link: https://syzkaller.appspot.com/bug?extid=e900ebe569e0c350092c
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e900eb...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 14339 Comm: blkid Not tainted 4.14.114 #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
task: ffff88805ca26640 task.stack: ffff888058cd8000
RIP: 0010:ax25_send_frame+0xd8/0x540 net/ax25/ax25_out.c:59
RSP: 0000:ffff8880aee07af8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88809b4c20c8 RCX: 1ffff1100b944deb
RDX: 0000000000000067 RSI: ffff88805ca26f38 RDI: 0000000000000338
RBP: ffff8880aee07b38 R08: ffff88805ca26640 R09: ffff88805ca26f58
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff89c1c0a0
R13: 0000000000000000 R14: 0000000000000104 R15: 0000000000000000
FS: 00007f7ef1aa9740(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7ef1663028 CR3: 00000000988ea000 CR4: 00000000001406f0
Call Trace:
kobject: 'loop3' (ffff8880a49992a0): kobject_uevent_env
<IRQ>
rose_send_frame+0xcd/0x270 net/rose/rose_link.c:111
kobject: 'loop3' (ffff8880a49992a0): fill_kobj_path: path
= '/devices/virtual/block/loop3'
rose_transmit_clear_request+0x1da/0x290 net/rose/rose_link.c:260
rose_rx_call_request+0x452/0x1940 net/rose/af_rose.c:999
rose_loopback_timer+0x232/0x3b0 net/rose/rose_loopback.c:103
kobject: 'loop4' (ffff8880a49ce1e0): kobject_uevent_env
call_timer_fn+0x164/0x680 kernel/time/timer.c:1279
kobject: 'loop4' (ffff8880a49ce1e0): fill_kobj_path: path
= '/devices/virtual/block/loop4'
expire_timers kernel/time/timer.c:1318 [inline]
__run_timers kernel/time/timer.c:1634 [inline]
__run_timers kernel/time/timer.c:1602 [inline]
run_timer_softirq+0x5b4/0x1570 kernel/time/timer.c:1647
__do_softirq+0x24e/0x9ae kernel/softirq.c:288
invoke_softirq kernel/softirq.c:368 [inline]
irq_exit+0x160/0x1b0 kernel/softirq.c:409
exiting_irq arch/x86/include/asm/apic.h:648 [inline]
smp_apic_timer_interrupt+0x156/0x600 arch/x86/kernel/apic/apic.c:1064
apic_timer_interrupt+0x8e/0xa0 arch/x86/entry/entry_64.S:787
</IRQ>
RIP: 0010:__mod_lruvec_page_state include/linux/memcontrol.h:610 [inline]
RIP: 0010:page_remove_file_rmap mm/rmap.c:1240 [inline]
RIP: 0010:page_remove_rmap+0x4ee/0x940 mm/rmap.c:1296
RSP: 0000:ffff888058cdfb20 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10
RAX: dffffc0000000000 RBX: ffff8880aa9fc000 RCX: 1ffffffff0ea51a4
RDX: 1ffff1101553f811 RSI: ffffffff8672a3c0 RDI: ffff8880aa9fc088
RBP: ffff888058cdfb50 R08: 0000000000000000 R09: ffff88805ca26f30
R10: ffff88805ca26f10 R11: ffff88805ca26640 R12: ffffea0000211c40
R13: ffffea0000211c60 R14: ffffffffffffffff R15: 0000000000000000
wp_page_copy+0x99a/0x1410 mm/memory.c:2567
do_wp_page+0x247/0x12b0 mm/memory.c:2778
handle_pte_fault mm/memory.c:3999 [inline]
__handle_mm_fault+0x1d4f/0x3470 mm/memory.c:4107
handle_mm_fault+0x293/0x7c0 mm/memory.c:4144
__do_page_fault+0x4c1/0xb80 arch/x86/mm/fault.c:1425
do_page_fault+0x71/0x515 arch/x86/mm/fault.c:1500
page_fault+0x45/0x50 arch/x86/entry/entry_64.S:1104
RIP: 0033:0x7f7ef189e789
RSP: 002b:00007ffe149ab8d0 EFLAGS: 00010216
RAX: 00007f7ef142e2a0 RBX: 00007f7ef1ab19a8 RCX: 00000000000004a8
RDX: 00007f7ef1663028 RSI: aaaaaaaaaaaaaaab RDI: 0000000000000000
RBP: 00007ffe149ab9b0 R08: 0000000000000001 R09: 0000000000000010
R10: 00007f7ef12fda30 R11: 0000000000000206 R12: 00007f7ef12df000
R13: 00007f7ef12fd220 R14: 00007f7ef12f7748 R15: 00007f7ef1aa9740
Code: e8 3e 84 00 00 48 85 c0 0f 85 9d 03 00 00 e8 b0 66 ec fb 49 8d bd 38
03 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 c5 03 00 00 49 8b 85 38 03 00 00 48 85 c0 48
RIP: ax25_send_frame+0xd8/0x540 net/ax25/ax25_out.c:59 RSP: ffff8880aee07af8
---[ end trace 00e299512d27f26e ]---


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[syzbot]

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