From: kernel test robot <oliver.sang@intel.com>
To: "Jim Cromie" <jim.cromie@gmail.com>,
"Łukasz Bartosik" <ukaszb@chromium.org>
Cc: <oe-lkp@lists.linux.dev>, <lkp@intel.com>, <oliver.sang@intel.com>
Subject: [jimc:dd-classmap-fix-3a] [dyndbg] 1aa71b32af: BUG:kernel_NULL_pointer_dereference,address
Date: Tue, 2 Jun 2026 21:09:42 +0800 [thread overview]
Message-ID: <202606021631.50f520ba-lkp@intel.com> (raw)
hi, Jim Cromie,
for this change, we reported
"[jimc:dd-shrink] [dyndbg] 1663ffb9c1: BUG:kernel_NULL_pointer_dereference,address"
in
https://lore.kernel.org/all/202601211325.7e1f336-lkp@intel.com/
at that time, we understood that you've already fixed it by a separate patch.
now we found the similar issue in another branch, we are not sure if this branch
is still active. so report out what we observe in our tests just FYI.
Hello,
kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on:
commit: 1aa71b32afe975c5402d381b16b95811b4ed16e4 ("dyndbg: resolve "protection" of class'd pr_debug")
https://github.com/jimc/linux.git dd-classmap-fix-3a
in testcase: boot
config: i386-randconfig-011-20250530
compiler: gcc-14
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 32G
(please refer to attached dmesg/kmsg for entire log/backtrace)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202606021631.50f520ba-lkp@intel.com
[ 0.646324][ T1] BUG: kernel NULL pointer dereference, address: 00000000
[ 0.647608][ T1] #PF: supervisor read access in kernel mode
[ 0.647608][ T1] #PF: error_code(0x0000) - not-present page
[ 0.647608][ T1] *pde = 00000000
[ 0.647608][ T1] Oops: Oops: 0000 [#1]
[ 0.647608][ T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Not tainted 7.1.0-rc4-00035-g1aa71b32afe9 #1 PREEMPT(full)
[ 0.647608][ T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[ 0.647608][ T1] EIP: strcmp (x86/lib/string_32.c:97)
[ 0.647608][ T1] Code: 84 c0 75 f7 31 c0 aa 89 d8 5b 5e 5f 5d e9 ff a7 01 00 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 55 89 e5 57 89 d7 56 89 c6 <ac> ae 75 08 84 c0 75 f8 31 c0 eb 04 19 c0 0c 01 5e 5f 5d e9 cf a7
All code
========
0: 84 c0 test %al,%al
2: 75 f7 jne 0xfffffffffffffffb
4: 31 c0 xor %eax,%eax
6: aa stos %al,%es:(%rdi)
7: 89 d8 mov %ebx,%eax
9: 5b pop %rbx
a: 5e pop %rsi
b: 5f pop %rdi
c: 5d pop %rbp
d: e9 ff a7 01 00 jmp 0x1a811
12: 2e 8d b4 26 00 00 00 cs lea 0x0(%rsi,%riz,1),%esi
19: 00
1a: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 57 push %rdi
25: 89 d7 mov %edx,%edi
27: 56 push %rsi
28: 89 c6 mov %eax,%esi
2a:* ac lods %ds:(%rsi),%al <-- trapping instruction
2b: ae scas %es:(%rdi),%al
2c: 75 08 jne 0x36
2e: 84 c0 test %al,%al
30: 75 f8 jne 0x2a
32: 31 c0 xor %eax,%eax
34: eb 04 jmp 0x3a
36: 19 c0 sbb %eax,%eax
38: 0c 01 or $0x1,%al
3a: 5e pop %rsi
3b: 5f pop %rdi
3c: 5d pop %rbp
3d: e9 .byte 0xe9
3e: cf iret
3f: a7 cmpsl %es:(%rdi),%ds:(%rsi)
Code starting with the faulting instruction
===========================================
0: ac lods %ds:(%rsi),%al
1: ae scas %es:(%rdi),%al
2: 75 08 jne 0xc
4: 84 c0 test %al,%al
6: 75 f8 jne 0x0
8: 31 c0 xor %eax,%eax
a: eb 04 jmp 0x10
c: 19 c0 sbb %eax,%eax
e: 0c 01 or $0x1,%al
10: 5e pop %rsi
11: 5f pop %rdi
12: 5d pop %rbp
13: e9 .byte 0xe9
14: cf iret
15: a7 cmpsl %es:(%rdi),%ds:(%rsi)
[ 0.647608][ T1] EAX: 00000000 EBX: 45489340 ECX: 00000000 EDX: 43a5414a
[ 0.647608][ T1] ESI: 00000000 EDI: 43a5414a EBP: 454a3e90 ESP: 454a3e88
[ 0.647608][ T1] DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068 EFLAGS: 00010217
[ 0.647608][ T1] CR0: 80050033 CR2: 00000000 CR3: 0440b000 CR4: 000006d0
[ 0.647608][ T1] Call Trace:
[ 0.647608][ T1] ? ddebug_add_module (dynamic_debug.c:1479 (discriminator 13))
[ 0.647608][ T1] ? blocking_notifier_chain_register (notifier.c:265 notifier.c:282)
[ 0.647608][ T1] ? dynamic_debug_init_control (dynamic_debug.c:1646)
[ 0.647608][ T1] ? dynamic_debug_init (dynamic_debug.c:1693)
[ 0.647608][ T1] ? dynamic_debug_init_control (dynamic_debug.c:1646)
[ 0.647608][ T1] ? do_one_initcall (main.c:1392)
[ 0.647608][ T1] ? __register_sysctl_init (proc/proc_sysctl.c:1436 proc/proc_sysctl.c:1465)
[ 0.647608][ T1] ? init_mm_internals (vmstat.c:2298)
[ 0.647608][ T1] ? kernel_init_freeable (main.c:1499 (discriminator 1) main.c:1692 (discriminator 1))
[ 0.647608][ T1] ? rest_init (main.c:762)
[ 0.647608][ T1] ? kernel_init (main.c:1593)
[ 0.647608][ T1] ? ret_from_fork (x86/kernel/process.c:158)
[ 0.647608][ T1] ? rest_init (main.c:762)
[ 0.647608][ T1] ? ret_from_fork_asm (x86/entry/entry_32.S:736)
[ 0.647608][ T1] ? entry_INT80_32 (x86/entry/entry_32.S:940)
[ 0.647608][ T1] Modules linked in:
[ 0.647608][ T1] CR2: 0000000000000000
[ 0.647608][ T1] ---[ end trace 0000000000000000 ]---
[ 0.647608][ T1] EIP: strcmp (x86/lib/string_32.c:97)
[ 0.647608][ T1] Code: 84 c0 75 f7 31 c0 aa 89 d8 5b 5e 5f 5d e9 ff a7 01 00 2e 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 55 89 e5 57 89 d7 56 89 c6 <ac> ae 75 08 84 c0 75 f8 31 c0 eb 04 19 c0 0c 01 5e 5f 5d e9 cf a7
All code
========
0: 84 c0 test %al,%al
2: 75 f7 jne 0xfffffffffffffffb
4: 31 c0 xor %eax,%eax
6: aa stos %al,%es:(%rdi)
7: 89 d8 mov %ebx,%eax
9: 5b pop %rbx
a: 5e pop %rsi
b: 5f pop %rdi
c: 5d pop %rbp
d: e9 ff a7 01 00 jmp 0x1a811
12: 2e 8d b4 26 00 00 00 cs lea 0x0(%rsi,%riz,1),%esi
19: 00
1a: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 57 push %rdi
25: 89 d7 mov %edx,%edi
27: 56 push %rsi
28: 89 c6 mov %eax,%esi
2a:* ac lods %ds:(%rsi),%al <-- trapping instruction
2b: ae scas %es:(%rdi),%al
2c: 75 08 jne 0x36
2e: 84 c0 test %al,%al
30: 75 f8 jne 0x2a
32: 31 c0 xor %eax,%eax
34: eb 04 jmp 0x3a
36: 19 c0 sbb %eax,%eax
38: 0c 01 or $0x1,%al
3a: 5e pop %rsi
3b: 5f pop %rdi
3c: 5d pop %rbp
3d: e9 .byte 0xe9
3e: cf iret
3f: a7 cmpsl %es:(%rdi),%ds:(%rsi)
Code starting with the faulting instruction
===========================================
0: ac lods %ds:(%rsi),%al
1: ae scas %es:(%rdi),%al
2: 75 08 jne 0xc
4: 84 c0 test %al,%al
6: 75 f8 jne 0x0
8: 31 c0 xor %eax,%eax
a: eb 04 jmp 0x10
c: 19 c0 sbb %eax,%eax
e: 0c 01 or $0x1,%al
10: 5e pop %rsi
11: 5f pop %rdi
12: 5d pop %rbp
13: e9 .byte 0xe9
14: cf iret
15: a7 cmpsl %es:(%rdi),%ds:(%rsi)
The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260602/202606021631.50f520ba-lkp@intel.com
--
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki
reply other threads:[~2026-06-02 13:10 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=202606021631.50f520ba-lkp@intel.com \
--to=oliver.sang@intel.com \
--cc=jim.cromie@gmail.com \
--cc=lkp@intel.com \
--cc=oe-lkp@lists.linux.dev \
--cc=ukaszb@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox