KASAN: out-of-bounds Read in update_stack_state (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: de620fb9 Merge branch 'for-5.4-fixes' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13ad7752e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=83de638b2a862933
dashboard link: https://syzkaller.appspot.com/bug?extid=878ce3f12fbfd888c942
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [b...@alien8.de h...@zytor.com ja...@google.com
jpoi...@redhat.com linux-...@vger.kernel.org mhir...@kernel.org
mi...@redhat.com pet...@infradead.org tg...@linutronix.de x...@kernel.org]

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+878ce3...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: out-of-bounds in update_stack_state+0x5de/0x5f0
arch/x86/kernel/unwind_frame.c:244
Read of size 8 at addr ffff88808a2c7b20 by task syz-executor.2/2004

CPU: 1 PID: 2004 Comm: syz-executor.2 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x197/0x210 lib/dump_stack.c:118
print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
__kasan_report.cold+0x1b/0x41 mm/kasan/report.c:506
kasan_report+0x12/0x20 mm/kasan/common.c:634
__asan_report_load8_noabort+0x14/0x20 mm/kasan/generic_report.c:132
update_stack_state+0x5de/0x5f0 arch/x86/kernel/unwind_frame.c:244
unwind_next_frame.part.0+0x1a9/0xa20 arch/x86/kernel/unwind_frame.c:311
unwind_next_frame+0x3b/0x50 arch/x86/kernel/unwind_frame.c:265
arch_stack_walk+0x81/0xf0 arch/x86/kernel/stacktrace.c:25
stack_trace_save_tsk+0x116/0x180 kernel/stacktrace.c:151
proc_pid_stack+0x111/0x200 fs/proc/base.c:454
proc_single_show+0xf0/0x170 fs/proc/base.c:756
seq_read+0x4ca/0x1110 fs/seq_file.c:229
do_loop_readv_writev fs/read_write.c:714 [inline]
do_loop_readv_writev fs/read_write.c:701 [inline]
do_iter_read+0x4a4/0x660 fs/read_write.c:935
vfs_readv+0xf0/0x160 fs/read_write.c:997
do_preadv+0x1c4/0x280 fs/read_write.c:1089
__do_sys_preadv fs/read_write.c:1139 [inline]
__se_sys_preadv fs/read_write.c:1134 [inline]
__x64_sys_preadv+0x9a/0xf0 fs/read_write.c:1134
do_syscall_64+0xfa/0x760 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a219
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff
ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffa6fa52c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 000000000045a219
RDX: 00000000000003a8 RSI: 00000000200017c0 RDI: 0000000000000004
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffa6fa536d4
R13: 00000000004c7a86 R14: 00000000004dd990 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea000228b1c0 refcount:0 mapcount:0 mapping:0000000000000000
index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 ffffffff02280101 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff88808a2c7a00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88808a2c7a80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ffff88808a2c7b00: 00 00 00 00 f1 f1 f1 f1 00 00 00 f2 f2 f2 00 00
^
ffff88808a2c7b80: 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
ffff88808a2c7c00: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 04 f3 f3
==================================================================


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[syzbot]

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