syzbot


KMSAN: uninit-value in exit_to_user_mode_loop (2)

Status: closed as invalid on 2021/09/28 12:42
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 431d, last: 431d
similar bugs (1):
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KMSAN: uninit-value in exit_to_user_mode_loop (3) C 2558 171d 429d 0/24 auto-closed as invalid on 2022/09/22 19:06

Sample crash report:
=====================================================
BUG: KMSAN: uninit-value in exit_to_user_mode_loop+0x464/0x490 kernel/entry/common.c:159
 exit_to_user_mode_loop+0x464/0x490 kernel/entry/common.c:159
 exit_to_user_mode_prepare kernel/entry/common.c:210 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x80/0xc0 kernel/entry/common.c:304
 __do_fast_syscall_32+0xa5/0xf0 arch/x86/entry/common.c:183
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c

Local variable ----regs@__bpf_prog_run32 created at:
 __bpf_prog_run32+0x84/0x180 kernel/bpf/core.c:1785
 bpf_dispatcher_nop_func include/linux/bpf.h:717 [inline]
 __bpf_prog_run include/linux/filter.h:624 [inline]
 bpf_prog_run include/linux/filter.h:631 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:1871 [inline]
 bpf_trace_run2+0x123/0x370 kernel/trace/bpf_trace.c:1908
=====================================================
Kernel panic - not syncing: panic_on_kmsan set ...
CPU: 1 PID: 14884 Comm: syz-executor.2 Tainted: G    B             5.15.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1ff/0x28e lib/dump_stack.c:106
 dump_stack+0x25/0x28 lib/dump_stack.c:113
 panic+0x44f/0xdeb kernel/panic.c:232
 kmsan_report+0x2ee/0x300 mm/kmsan/report.c:186
 __msan_warning+0xd7/0x150 mm/kmsan/instrumentation.c:208
 exit_to_user_mode_loop+0x464/0x490 kernel/entry/common.c:159
 exit_to_user_mode_prepare kernel/entry/common.c:210 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x80/0xc0 kernel/entry/common.c:304
 __do_fast_syscall_32+0xa5/0xf0 arch/x86/entry/common.c:183
 do_fast_syscall_32+0x34/0x70 arch/x86/entry/common.c:205
 do_SYSENTER_32+0x1b/0x20 arch/x86/entry/common.c:248
 entry_SYSENTER_compat_after_hwframe+0x4d/0x5c
RIP: 0023:0xf6f53549
Code: 03 74 c0 01 10 05 03 74 b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00
RSP: 002b:00000000f454d68c EFLAGS: 00000246 ORIG_RAX: 00000000000000f0
RAX: 0000000000000001 RBX: 00000000f70affac RCX: 0000000000000081
RDX: 00000000000f4240 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00000000f6f6a6a9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Kernel Offset: disabled
Rebooting in 86400 seconds..
----------------
Code disassembly (best guess):
   0:	03 74 c0 01          	add    0x1(%rax,%rax,8),%esi
   4:	10 05 03 74 b8 01    	adc    %al,0x1b87403(%rip)        # 0x1b8740d
   a:	10 06                	adc    %al,(%rsi)
   c:	03 74 b4 01          	add    0x1(%rsp,%rsi,4),%esi
  10:	10 07                	adc    %al,(%rdi)
  12:	03 74 b0 01          	add    0x1(%rax,%rsi,4),%esi
  16:	10 08                	adc    %cl,(%rax)
  18:	03 74 d8 01          	add    0x1(%rax,%rbx,8),%esi
  1c:	00 00                	add    %al,(%rax)
  1e:	00 00                	add    %al,(%rax)
  20:	00 51 52             	add    %dl,0x52(%rcx)
  23:	55                   	push   %rbp
  24:	89 e5                	mov    %esp,%ebp
  26:	0f 34                	sysenter
  28:	cd 80                	int    $0x80
* 2a:	5d                   	pop    %rbp <-- trapping instruction
  2b:	5a                   	pop    %rdx
  2c:	59                   	pop    %rcx
  2d:	c3                   	retq
  2e:	90                   	nop
  2f:	90                   	nop
  30:	90                   	nop
  31:	90                   	nop
  32:	66 2e 0f 1f 84 00 00 	nopw   %cs:0x0(%rax,%rax,1)
  39:	00 00 00
  3c:	0f                   	.byte 0xf
  3d:	1f                   	(bad)
  3e:	44                   	rex.R

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci-upstream-kmsan-gce-386 2021/09/28 05:58 https://github.com/google/kmsan.git master cd2c05533838 78494d16 .config log report info KMSAN: uninit-value in exit_to_user_mode_loop
* Struck through repros no longer work on HEAD.