2021-06-28 20:35:41

by kernel test robot

[permalink] [raw]
Subject: [selftests/lkdtm] 7ecfffe9bc: kernel_BUG_at_drivers/misc/lkdtm/bugs.c



Greeting,

FYI, we noticed the following commit (built with gcc-9):

commit: 7ecfffe9bcb6657ae3a86c58f8eae2fe37b54807 ("selftests/lkdtm: Avoid needing explicit sub-shell")
https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git for-next/lkdtm


in testcase: kernel-selftests
version: kernel-selftests-x86_64-f8879e85-1_20210621
with following parameters:

group: lkdtm
ucode: 0xe2

test-description: The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small unit tests to exercise individual code paths in the kernel.
test-url: https://www.kernel.org/doc/Documentation/kselftest.txt


on test machine: 4 threads Intel(R) Core(TM) i5-6500 CPU @ 3.20GHz with 32G memory

caused below changes (please refer to attached dmesg/kmsg for entire log/backtrace):



If you fix the issue, kindly add following tag
Reported-by: kernel test robot <[email protected]>


[ 47.248291] kernel BUG at drivers/misc/lkdtm/bugs.c:76!
[ 47.253682] invalid opcode: 0000 [#1] PREEMPT SMP PTI
[ 47.258745] CPU: 0 PID: 1432 Comm: cat Not tainted 5.13.0-rc2-00001-g7ecfffe9bcb6 #1
[ 47.266509] Hardware name: Dell Inc. OptiPlex 7040/0Y7WYT, BIOS 1.8.1 12/05/2017
[ 47.273922] RIP: 0010:lkdtm_BUG (drivers/misc/lkdtm/bugs.c:76)
[ 47.277856] Code: cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 <0f> 0b 66 66 2e 0f 1f 84 00 00 00 00 00 66 66 2e 0f 1f 84 00 00 00
All code
========
0: cc int3
1: cc int3
2: cc int3
3: cc int3
4: cc int3
5: cc int3
6: cc int3
7: cc int3
8: cc int3
9: cc int3
a: cc int3
b: cc int3
c: cc int3
d: cc int3
e: cc int3
f: cc int3
10: cc int3
11: cc int3
12: cc int3
13: cc int3
14: cc int3
15: cc int3
16: cc int3
17: cc int3
18: cc int3
19: cc int3
1a: cc int3
1b: cc int3
1c: cc int3
1d: cc int3
1e: cc int3
1f: cc int3
20: cc int3
21: cc int3
22: cc int3
23: cc int3
24: cc int3
25: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1)
2a:* 0f 0b ud2 <-- trapping instruction
2c: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
33: 00 00 00 00
37: 66 data16
38: 66 data16
39: 2e cs
3a: 0f .byte 0xf
3b: 1f (bad)
3c: 84 00 test %al,(%rax)
...

Code starting with the faulting instruction
===========================================
0: 0f 0b ud2
2: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
9: 00 00 00 00
d: 66 data16
e: 66 data16
f: 2e cs
10: 0f .byte 0xf
11: 1f (bad)
12: 84 00 test %al,(%rax)
...
[ 47.296687] RSP: 0018:ffffc90001447e58 EFLAGS: 00010282
[ 47.301926] RAX: ffffffff81992280 RBX: 0000000000000001 RCX: 0000000000000000
[ 47.309079] RDX: 0000000000000000 RSI: ffffffff8122f88f RDI: ffffffff824c3f30
[ 47.316231] RBP: ffff888814b1a000 R08: 0000000000000001 R09: 0000000000000001
[ 47.323386] R10: 0000000000000001 R11: 0000000000000001 R12: 0000000000000004
[ 47.330540] R13: ffffc90001447f08 R14: ffffffff828b9198 R15: ffff888102666270
[ 47.337695] FS: 00007fb5044ea540(0000) GS:ffff88881dc00000(0000) knlGS:0000000000000000
[ 47.345806] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 47.351567] CR2: 00007fb504160000 CR3: 0000000814b30006 CR4: 00000000003706f0
[ 47.358719] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 47.365874] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 47.373028] Call Trace:
[ 47.375480] direct_entry.cold (drivers/misc/lkdtm/core.c:397)
[ 47.379417] full_proxy_write (fs/debugfs/file.c:234)
[ 47.383262] vfs_write (fs/read_write.c:603)
[ 47.386587] ksys_write (fs/read_write.c:658)
[ 47.389996] do_syscall_64 (arch/x86/entry/common.c:47)
[ 47.393582] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:112)
[ 47.398652] RIP: 0033:0x7fb504412504
[ 47.402241] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 48 8d 05 f9 61 0d 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 49 89 d4 55 48 89 f5 53
All code
========
0: 00 f7 add %dh,%bh
2: d8 64 89 02 fsubs 0x2(%rcx,%rcx,4)
6: 48 c7 c0 ff ff ff ff mov $0xffffffffffffffff,%rax
d: eb b3 jmp 0xffffffffffffffc2
f: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
16: 48 8d 05 f9 61 0d 00 lea 0xd61f9(%rip),%rax # 0xd6216
1d: 8b 00 mov (%rax),%eax
1f: 85 c0 test %eax,%eax
21: 75 13 jne 0x36
23: b8 01 00 00 00 mov $0x1,%eax
28: 0f 05 syscall
2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction
30: 77 54 ja 0x86
32: c3 retq
33: 0f 1f 00 nopl (%rax)
36: 41 54 push %r12
38: 49 89 d4 mov %rdx,%r12
3b: 55 push %rbp
3c: 48 89 f5 mov %rsi,%rbp
3f: 53 push %rbx

Code starting with the faulting instruction
===========================================
0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax
6: 77 54 ja 0x5c
8: c3 retq
9: 0f 1f 00 nopl (%rax)
c: 41 54 push %r12
e: 49 89 d4 mov %rdx,%r12
11: 55 push %rbp
12: 48 89 f5 mov %rsi,%rbp
15: 53 push %rbx


To reproduce:

git clone https://github.com/intel/lkp-tests.git
cd lkp-tests
bin/lkp install job.yaml # job file is attached in this email
bin/lkp split-job --compatible job.yaml # generate the yaml file for lkp run
bin/lkp run generated-yaml-file



---
0DAY/LKP+ Test Infrastructure Open Source Technology Center
https://lists.01.org/hyperkitty/list/[email protected] Intel Corporation

Thanks,
Oliver Sang


Attachments:
(No filename) (7.16 kB)
config-5.13.0-rc2-00001-g7ecfffe9bcb6 (178.12 kB)
job-script (5.98 kB)
dmesg.xz (21.36 kB)
job.yaml (4.85 kB)
Download all attachments

2021-06-28 23:37:26

by Kees Cook

[permalink] [raw]
Subject: Re: [selftests/lkdtm] 7ecfffe9bc: kernel_BUG_at_drivers/misc/lkdtm/bugs.c

On Mon, Jun 28, 2021 at 10:59:22PM +0800, kernel test robot wrote:
>
>
> Greeting,
>
> FYI, we noticed the following commit (built with gcc-9):
>
> commit: 7ecfffe9bcb6657ae3a86c58f8eae2fe37b54807 ("selftests/lkdtm: Avoid needing explicit sub-shell")
> https://git.kernel.org/cgit/linux/kernel/git/kees/linux.git for-next/lkdtm
>
>
> in testcase: kernel-selftests
> version: kernel-selftests-x86_64-f8879e85-1_20210621
> with following parameters:
>
> group: lkdtm
> ucode: 0xe2
>
> test-description: The kernel contains a set of "self tests" under the tools/testing/selftests/ directory. These are intended to be small unit tests to exercise individual code paths in the kernel.
> test-url: https://www.kernel.org/doc/Documentation/kselftest.txt

When running the "lkdtm" subsystem of tests, CI systems should ignore
console Oopses, since those are "working as intended" for lkdtm (which
is explicitly testing for those Oopses).

-Kees

--
Kees Cook