[jimc:dd-classmap-fix-3a] [dyndbg] 1aa71b32af: BUG:kernel_NULL_pointer_dereference,address
kernel test robot <[email protected]> Tue, 2 Jun 2026 21:09:42 +0800
| Newsgroups | dev.linux.lists.oe-lkp |
|---|---|
| Message-ID | <[email protected]> |
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/[email protected]/ 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 <[email protected]> | Closes: https://lore.kernel.org/oe-lkp/[email protected] [ 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/[email protected] -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki