KASAN: unknown-crash Read in do_exit (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 7ddb58cb0eca Merge tag 'clk-for-linus' of git://git.kernel..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15308fcab00000
kernel config: https://syzkaller.appspot.com/x/.config?x=a30ce238f371e547
dashboard link: https://syzkaller.appspot.com/bug?extid=fb39d56110148ccdd11d
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [ax...@kernel.dk chri...@brauner.io ebie...@xmission.com jnew...@torproject.org kees...@chromium.org linux-...@vger.kernel.org ol...@redhat.com tg...@linutronix.de]

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+fb39d5...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: unknown-crash in stack_not_used include/linux/sched/task_stack.h:105 [inline]
BUG: KASAN: unknown-crash in check_stack_usage kernel/exit.c:716 [inline]
BUG: KASAN: unknown-crash in do_exit+0x25d5/0x2b40 kernel/exit.c:875
Read of size 8 at addr ffffc9000504ce20 by task syz-executor.0/19971

CPU: 1 PID: 19971 Comm: syz-executor.0 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xf/0x309 mm/kasan/report.c:256
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
stack_not_used include/linux/sched/task_stack.h:105 [inline]
check_stack_usage kernel/exit.c:716 [inline]
do_exit+0x25d5/0x2b40 kernel/exit.c:875
do_group_exit+0x125/0x310 kernel/exit.c:929
get_signal+0x47d/0x21d0 kernel/signal.c:2820
arch_do_signal_or_restart+0x2a9/0x1c40 arch/x86/kernel/signal.c:868
handle_signal_work kernel/entry/common.c:148 [inline]
exit_to_user_mode_loop kernel/entry/common.c:172 [inline]
exit_to_user_mode_prepare+0x17d/0x290 kernel/entry/common.c:207
__syscall_exit_to_user_mode_work kernel/entry/common.c:289 [inline]
syscall_exit_to_user_mode+0x19/0x60 kernel/entry/common.c:300
do_syscall_64+0x42/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7fd225673ae9
Code: Unable to access opcode bytes at RIP 0x7fd225673abf.
RSP: 002b:00007fd222be9188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffed RBX: 00007fd225786f60 RCX: 00007fd225673ae9
RDX: 0000000000000000 RSI: 0000000020000140 RDI: 0000000020000100
RBP: 00007fd2256cdf25 R08: 00000000200001c0 R09: 0000000000000000
R10: 0000000000000401 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe5abdabbf R14: 00007fd222be9300 R15: 0000000000022000
</TASK>


Memory state around the buggy address:
ffffc9000504cd00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc9000504cd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffffc9000504ce00: 00 00 00 00 77 77 77 77 00 00 00 00 00 00 00 00
^
ffffc9000504ce80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffffc9000504cf00: 00 00 00 00 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.