[jimc:dd-ratelimit] [dyndbg] b65e77782e: BUG:kernel_NULL_pointer_dereference,address

kernel test robot <[email protected]> Fri, 10 Jul 2026 09:31:32 +0800
Newsgroups dev.linux.lists.oe-lkp
Message-ID <[email protected]>

Hello,

kernel test robot noticed "BUG:kernel_NULL_pointer_dereference,address" on:

commit: b65e77782ef0e657869ec5093935ffdda0cb4b28 ("dyndbg: consolidate site ranges")
https://github.com/jimc/linux.git dd-ratelimit

in testcase: boot

config: i386-randconfig-011-20260706
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 <[email protected]>
| Closes: https://lore.kernel.org/oe-lkp/[email protected]



[    7.855146][  T112] BUG: kernel NULL pointer dereference, address: 00000000
[    7.857470][  T112] #PF: supervisor read access in kernel mode
[    7.859313][  T112] #PF: error_code(0x0000) - not-present page
[    7.861248][  T112] *pde = 00000000
[    7.862470][  T112] Oops: Oops: 0000 [#1] SMP
[    7.863891][  T112] CPU: 0 UID: 0 PID: 112 Comm: systemd-udevd Tainted: G        W           7.2.0-rc1-00062-gb65e77782ef0 #1 PREEMPT(lazy)  d791b41899d215960b78e1ce16355c682d1dd07f
[    7.868778][  T112] Tainted: [W]=WARN
[    7.869984][  T112] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    7.872988][  T112] EIP: strcmp+0xa/0x20
[    7.874870][  T112] Code: 31 c0 83 c9 ff f2 ae 4f 8b 4d f0 49 78 06 ac aa 84 c0 75 f7 31 c0 aa 5e 89 d8 5b 5e 5f 5d c3 90 55 89 e5 57 56 89 d7 89 c6 ac <ae> 75 08 84 c0 75 f8 31 c0 eb 04 19 c0 0c 01 5e 5f 5d c3 8d 76 00
All code
========
   0:	31 c0                	xor    %eax,%eax
   2:	83 c9 ff             	or     $0xffffffff,%ecx
   5:	f2 ae                	repnz scas %es:(%rdi),%al
   7:	4f 8b 4d f0          	rex.WRXB mov -0x10(%r13),%r9
   b:	49 78 06             	rex.WB js 0x14
   e:	ac                   	lods   %ds:(%rsi),%al
   f:	aa                   	stos   %al,%es:(%rdi)
  10:	84 c0                	test   %al,%al
  12:	75 f7                	jne    0xb
  14:	31 c0                	xor    %eax,%eax
  16:	aa                   	stos   %al,%es:(%rdi)
  17:	5e                   	pop    %rsi
  18:	89 d8                	mov    %ebx,%eax
  1a:	5b                   	pop    %rbx
  1b:	5e                   	pop    %rsi
  1c:	5f                   	pop    %rdi
  1d:	5d                   	pop    %rbp
  1e:	c3                   	ret
  1f:	90                   	nop
  20:	55                   	push   %rbp
  21:	89 e5                	mov    %esp,%ebp
  23:	57                   	push   %rdi
  24:	56                   	push   %rsi
  25:	89 d7                	mov    %edx,%edi
  27:	89 c6                	mov    %eax,%esi
  29:	ac                   	lods   %ds:(%rsi),%al
  2a:*	ae                   	scas   %es:(%rdi),%al		<-- trapping instruction
  2b:	75 08                	jne    0x35
  2d:	84 c0                	test   %al,%al
  2f:	75 f8                	jne    0x29
  31:	31 c0                	xor    %eax,%eax
  33:	eb 04                	jmp    0x39
  35:	19 c0                	sbb    %eax,%eax
  37:	0c 01                	or     $0x1,%al
  39:	5e                   	pop    %rsi
  3a:	5f                   	pop    %rdi
  3b:	5d                   	pop    %rbp
  3c:	c3                   	ret
  3d:	8d 76 00             	lea    0x0(%rsi),%esi

Code starting with the faulting instruction
===========================================
   0:	ae                   	scas   %es:(%rdi),%al
   1:	75 08                	jne    0xb
   3:	84 c0                	test   %al,%al
   5:	75 f8                	jne    0xffffffffffffffff
   7:	31 c0                	xor    %eax,%eax
   9:	eb 04                	jmp    0xf
   b:	19 c0                	sbb    %eax,%eax
   d:	0c 01                	or     $0x1,%al
   f:	5e                   	pop    %rsi
  10:	5f                   	pop    %rdi
  11:	5d                   	pop    %rbp
  12:	c3                   	ret
  13:	8d 76 00             	lea    0x0(%rsi),%esi
[    7.878857][  T112] EAX: f78a2071 EBX: 4161ebf0 ECX: f78ab00c EDX: 00000000
[    7.880299][  T112] ESI: f78a2009 EDI: 00000000 EBP: 57fd1b24 ESP: 57fd1b1c
[    7.881734][  T112] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00210282
[    7.883357][  T112] CR0: 80050033 CR2: 00000000 CR3: 17fb6000 CR4: 00040690
[    7.884788][  T112] Call Trace:
[    7.885500][  T112]  ? ddebug_grow_tree+0x9a/0x110
[    7.886521][  T112]  ? ddebug_condense_sites+0x68/0xe0
[    7.887595][  T112]  ? ddebug_get_filename+0x10/0x10
[    7.888640][  T112]  ? ddebug_get_function+0x10/0x10
[    7.890488][  T112]  ? ddebug_proc_next+0x40/0x40
[    7.891513][  T112]  ? ddebug_add_module+0x85/0x500
[    7.892553][  T112]  ? preempt_count_add+0x51/0x60
[    7.893587][  T112]  ? __mutex_unlock_slowpath+0x2de/0x300
[    7.894736][  T112]  ? mutex_unlock+0xb/0x10
[    7.895651][  T112]  ? ddebug_add_module+0x500/0x500
[    7.896723][  T112]  ? ddebug_module_notify+0x41/0xd0
[    7.897798][  T112]  ? notifier_call_chain+0xc7/0xf0
[    7.898847][  T112]  ? notifier_call_chain_robust+0x20/0x50
[    7.900036][  T112]  ? blocking_notifier_call_chain_robust+0x31/0x50
[    7.901380][  T112]  ? load_module+0x496/0x6e0
[    7.902353][  T112]  ? init_module_from_file+0x78/0x80
[    7.903440][  T112]  ? __ia32_sys_finit_module+0x149/0x220
[    7.904603][  T112]  ? ia32_sys_call+0xccd/0x1110
[    7.905619][  T112]  ? do_int80_syscall_32+0x11a/0x260
[    7.906713][  T112]  ? lockdep_hardirqs_on+0xe0/0x110
[    7.907776][  T112]  ? do_int80_syscall_32+0x258/0x260
[    7.908874][  T112]  ? sched_clock_noinstr+0x8/0x10
[    7.909925][  T112]  ? __bpf_prog_run32+0x3a/0x50
[    7.910947][  T112]  ? __bpf_prog_run32+0x3a/0x50
[    7.911962][  T112]  ? debug_smp_processor_id+0x12/0x20
[    7.913105][  T112]  ? get_lock_stats+0x12/0x50
[    7.914085][  T112]  ? preempt_latency_start+0x1f/0x50
[    7.915184][  T112]  ? preempt_count_add+0x51/0x60
[    7.916212][  T112]  ? seccomp_run_filters+0x285/0x2b0
[    7.917317][  T112]  ? debug_smp_processor_id+0x12/0x20
[    7.918399][  T112]  ? __seccomp_filter+0x9c/0x1f0
[    7.919401][  T112]  ? do_int80_syscall_32+0xd7/0x260
[    7.920481][  T112]  ? entry_INT80_32+0xf0/0xf0
[    7.921480][  T112] Modules linked in: qemu_fw_cfg(+) intel_gtt agpgart autofs4
[    7.923058][  T112] CR2: 0000000000000000
[    7.924040][  T112] ---[ end trace 0000000000000000 ]---
[  OK  ] Finished Coldplug All udev Devices.
[  OK  ] Reached target System Initialization.


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20260709/[email protected]



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki