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* [sailus-media-tree:media-ref] [media]  696502a495: BUG:kernel_NULL_pointer_dereference,address
@ 2026-10-27  3:07 kernel test robot
  0 siblings, 0 replies; only message in thread
From: kernel test robot @ 2026-10-27  3:07 UTC (permalink / raw)
  To: Sakari Ailus; +Cc: oe-lkp, lkp, linux-media, yi1.lai



Hello,

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

commit: 696502a4953ea062964ebe1f3b1a09a9d6c8a591 ("media: mc: Implement best effort media device removal safety sans refcount") git://linuxtv.org/sailus/media_tree.git media-ref

in testcase: boot

config: i386-randconfig-011-20250511
compiler: gcc-14
test machine: qemu-system-i386 -enable-kvm -cpu Icelake-Server-noTSX,enforce,lm=off -smp 4 -m 4G

(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 <yi1.lai@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202610271039.7cc92f63-lkp@intel.com


[    5.959887][    T1] BUG: kernel NULL pointer dereference, address: 00000000
[    5.961338][    T1] #PF: supervisor read access in kernel mode
[    5.962189][    T1] #PF: error_code(0x0000) - not-present page
[    5.962189][    T1] *pde = 00000000
[    5.962189][    T1] Oops: Oops: 0000 [#1] SMP
[    5.962189][    T1] CPU: 0 UID: 0 PID: 1 Comm: swapper/0 Tainted: G                T   7.3.0-rc1+ #1 PREEMPT(full)
[    5.962189][    T1] Tainted: [T]=RANDSTRUCT
[    5.962189][    T1] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[    5.962189][    T1] EIP: strlen (x86/lib/string_32.c:148)
[    5.962189][    T1] Code: c4 ac 38 e0 74 09 84 c0 75 f7 be 01 00 00 00 89 f0 48 5e 5d 31 d2 c3 8d 76 00 3e 8d 74 26 00 55 83 c9 ff 89 e5 57 89 c7 31 c0 <f2> ae b8 fe ff ff ff 5f 5d 29 c8 31 c9 c3 66 90 3e 8d 74 26 00 85
All code
========
   0:	c4                   	(bad)
   1:	ac                   	lods   %ds:(%rsi),%al
   2:	38 e0                	cmp    %ah,%al
   4:	74 09                	je     0xf
   6:	84 c0                	test   %al,%al
   8:	75 f7                	jne    0x1
   a:	be 01 00 00 00       	mov    $0x1,%esi
   f:	89 f0                	mov    %esi,%eax
  11:	48 5e                	rex.W pop %rsi
  13:	5d                   	pop    %rbp
  14:	31 d2                	xor    %edx,%edx
  16:	c3                   	ret
  17:	8d 76 00             	lea    0x0(%rsi),%esi
  1a:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  1f:	55                   	push   %rbp
  20:	83 c9 ff             	or     $0xffffffff,%ecx
  23:	89 e5                	mov    %esp,%ebp
  25:	57                   	push   %rdi
  26:	89 c7                	mov    %eax,%edi
  28:	31 c0                	xor    %eax,%eax
  2a:*	f2 ae                	repnz scas %es:(%rdi),%al		<-- trapping instruction
  2c:	b8 fe ff ff ff       	mov    $0xfffffffe,%eax
  31:	5f                   	pop    %rdi
  32:	5d                   	pop    %rbp
  33:	29 c8                	sub    %ecx,%eax
  35:	31 c9                	xor    %ecx,%ecx
  37:	c3                   	ret
  38:	66 90                	xchg   %ax,%ax
  3a:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  3f:	85                   	.byte 0x85

Code starting with the faulting instruction ===========================================
   0:	f2 ae                	repnz scas %es:(%rdi),%al
   2:	b8 fe ff ff ff       	mov    $0xfffffffe,%eax
   7:	5f                   	pop    %rdi
   8:	5d                   	pop    %rbp
   9:	29 c8                	sub    %ecx,%eax
   b:	31 c9                	xor    %ecx,%ecx
   d:	c3                   	ret
   e:	66 90                	xchg   %ax,%ax
  10:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  15:	85                   	.byte 0x85
[    5.962189][    T1] EAX: 00000000 EBX: 87846e08 ECX: ffffffff EDX: 00000000
[    5.962189][    T1] ESI: 00000000 EDI: 00000000 EBP: 80be5d90 ESP: 80be5d8c
[    5.962189][    T1] DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010246
[    5.962189][    T1] CR0: 80050033 CR2: 00000000 CR3: 0347f000 CR4: 003506d0
[    5.962189][    T1] Call Trace:
[    5.962189][    T1]  simple_start_creating (linux/fortify-string.h:218 libfs.c:2302)
[    5.962189][    T1]  ? simple_pin_fs (libfs.c:1112)
[    5.962189][    T1]  debugfs_start_creating (debugfs/inode.c:397 debugfs/inode.c:362)
[    5.962189][    T1]  debugfs_create_dir (debugfs/inode.c:575)
[    5.962189][    T1]  __media_device_register (media/mc/mc-device.c:892 (discriminator 1))
[    5.962189][    T1]  vicodec_probe (media/test-drivers/vicodec/vicodec-core.c:2180)
[    5.962189][    T1]  platform_probe (base/platform.c:1507)
[    5.962189][    T1]  really_probe (base/dd.c:628 base/dd.c:706)
[    5.962189][    T1]  __driver_probe_device (base/dd.c:868)
[    5.962189][    T1]  driver_probe_device (base/dd.c:898)
[    5.962189][    T1]  __driver_attach (base/dd.c:1292 base/dd.c:1232)
[    5.962189][    T1]  ? __device_attach_driver (base/dd.c:1030)
[    5.962189][    T1]  bus_for_each_dev (base/bus.c:383)
[    5.962189][    T1]  driver_attach (base/dd.c:1310)
[    5.962189][    T1]  ? __device_attach_driver (base/dd.c:1030)
[    5.962189][    T1]  bus_add_driver (base/bus.c:763)
[    5.962189][    T1]  driver_register (base/driver.c:174)
[    5.962189][    T1]  __platform_driver_register (base/platform.c:995)
[    5.962189][    T1]  vicodec_init (media/test-drivers/vicodec/vicodec-core.c:2254)
[    5.962189][    T1]  ? cxd2880_spi_driver_init (media/spi/cxd2880-spi.c:663)
[    5.962189][    T1]  do_one_initcall (main.c:1357)
[    5.962189][    T1]  ? rdinit_setup (main.c:595)
[    5.962189][    T1]  ? debug_smp_processor_id (smp_processor_id.c:58)
[    5.962189][    T1]  ? rcu_is_watching (linux/context_tracking.h:128 rcu/tree.c:753)
[    5.962189][    T1]  do_initcalls (main.c:1419 (discriminator 1) main.c:1435 (discriminator 1))
[    5.962189][    T1]  kernel_init_freeable (main.c:1455 main.c:1670)
[    5.962189][    T1]  ? rest_init (main.c:727)
[    5.962189][    T1]  kernel_init (main.c:1560)
[    5.962189][    T1]  ret_from_fork (x86/kernel/process.c:158)
[    5.962189][    T1]  ? rest_init (main.c:727)
[    5.962189][    T1]  ret_from_fork_asm (x86/entry/entry_32.S:736)
[    5.962189][    T1]  entry_INT80_32 (x86/entry/entry_32.S:940)
[    5.962189][    T1] Modules linked in:
[    5.962189][    T1] CR2: 0000000000000000
[    5.962189][    T1] ---[ end trace 0000000000000000 ]---
[    5.962189][    T1] EIP: strlen (x86/lib/string_32.c:148)
[    5.962189][    T1] Code: c4 ac 38 e0 74 09 84 c0 75 f7 be 01 00 00 00 89 f0 48 5e 5d 31 d2 c3 8d 76 00 3e 8d 74 26 00 55 83 c9 ff 89 e5 57 89 c7 31 c0 <f2> ae b8 fe ff ff ff 5f 5d 29 c8 31 c9 c3 66 90 3e 8d 74 26 00 85
All code
========
   0:	c4                   	(bad)
   1:	ac                   	lods   %ds:(%rsi),%al
   2:	38 e0                	cmp    %ah,%al
   4:	74 09                	je     0xf
   6:	84 c0                	test   %al,%al
   8:	75 f7                	jne    0x1
   a:	be 01 00 00 00       	mov    $0x1,%esi
   f:	89 f0                	mov    %esi,%eax
  11:	48 5e                	rex.W pop %rsi
  13:	5d                   	pop    %rbp
  14:	31 d2                	xor    %edx,%edx
  16:	c3                   	ret
  17:	8d 76 00             	lea    0x0(%rsi),%esi
  1a:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  1f:	55                   	push   %rbp
  20:	83 c9 ff             	or     $0xffffffff,%ecx
  23:	89 e5                	mov    %esp,%ebp
  25:	57                   	push   %rdi
  26:	89 c7                	mov    %eax,%edi
  28:	31 c0                	xor    %eax,%eax
  2a:*	f2 ae                	repnz scas %es:(%rdi),%al		<-- trapping instruction
  2c:	b8 fe ff ff ff       	mov    $0xfffffffe,%eax
  31:	5f                   	pop    %rdi
  32:	5d                   	pop    %rbp
  33:	29 c8                	sub    %ecx,%eax
  35:	31 c9                	xor    %ecx,%ecx
  37:	c3                   	ret
  38:	66 90                	xchg   %ax,%ax
  3a:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  3f:	85                   	.byte 0x85

Code starting with the faulting instruction ===========================================
   0:	f2 ae                	repnz scas %es:(%rdi),%al
   2:	b8 fe ff ff ff       	mov    $0xfffffffe,%eax
   7:	5f                   	pop    %rdi
   8:	5d                   	pop    %rbp
   9:	29 c8                	sub    %ecx,%eax
   b:	31 c9                	xor    %ecx,%ecx
   d:	c3                   	ret
   e:	66 90                	xchg   %ax,%ax
  10:	3e 8d 74 26 00       	ds lea 0x0(%rsi,%riz,1),%esi
  15:	85                   	.byte 0x85


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20261027/202610271039.7cc92f63-lkp@intel.com


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



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