syzbot


KASAN: unknown-crash Read in do_exit (2)
Status: auto-closed as invalid on 2022/02/02 23:28
Reported-by: syzbot+fb39d56110148ccdd11d@syzkaller.appspotmail.com
First crash: 203d, last: 203d
similar bugs (2):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: unknown-crash Read in do_exit C inconclusive done 2 615d 620d 17/22 fixed on 2020/11/16 12:12
upstream KASAN: out-of-bounds Read in do_exit 1 342d 337d 0/22 auto-closed as invalid on 2021/10/17 21:26

Sample crash report:
==================================================================
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
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kasan-gce-root 2021/11/04 23:27 upstream 7ddb58cb0eca 4c1be0be .config log report info KASAN: unknown-crash Read in do_exit