KASAN: out-of-bounds Read in exit_to_usermode_loop

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cbfa1702 Linux 4.14.198
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1595a8fb900000
kernel config: https://syzkaller.appspot.com/x/.config?x=3990958d85b55e59
dashboard link: https://syzkaller.appspot.com/bug?extid=25468ef861884b9c0b93
compiler: gcc (GCC) 10.1.0-syz 20200507

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+25468e...@syzkaller.appspotmail.com

IPv6: ADDRCONF(NETDEV_UP): veth0_virt_wifi: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_virt_wifi: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_virt_wifi: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_virt_wifi: link becomes ready
==================================================================
BUG: KASAN: out-of-bounds in arch_local_irq_disable arch/x86/include/asm/paravirt.h:784 [inline]
BUG: KASAN: out-of-bounds in exit_to_usermode_loop+0x1cf/0x200 arch/x86/entry/common.c:174
Read of size 8 at addr ffffffff87d16910 by task modprobe/9604

CPU: 1 PID: 9604 Comm: modprobe Not tainted 4.14.198-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x283 lib/dump_stack.c:58
print_address_description.cold+0x5/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load8_noabort+0x68/0x70 mm/kasan/report.c:430
arch_local_irq_disable arch/x86/include/asm/paravirt.h:784 [inline]
exit_to_usermode_loop+0x1cf/0x200 arch/x86/entry/common.c:174

The buggy address belongs to the variable:
pv_irq_ops+0x10/0x30

Memory state around the buggy address:
ffffffff87d16800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffffff87d16880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffffff87d16900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
^
ffffffff87d16980: 00 00 00 00 00 00 00 00 00 00 00 00 00 fa fa fa
ffffffff87d16a00: fa fa fa fa 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


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[syzbot]

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