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kernel BUG in jfs_unlink

Status: upstream: reported C repro on 2024/07/24 18:05
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+41b43444de86db4c5ed1@syzkaller.appspotmail.com
First crash: 666d, last: 16d
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
ff2d10d9-d197-4aed-8159-12d74686f6a5 assessment-security 💥 kernel BUG in jfs_unlink 2026/05/15 17:22 2026/05/15 17:22 2026/05/15 17:50 efdaf0f9b8bfc56ea6d17bea15a64f4591cc712d failed to run ["make" "KERNELVERSION=syzkaller" "KERNELRELEASE=syzkaller" "LOCALVERSION=-syzkaller" "-j" "32" "ARCH=x86_64" "CC=ccache clang" "LD=ld.lld" "O=/app/workdir/cache/build/441ccb086b3e7b3a2441b7a6efa8e3bb07d0fed6" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: ld.lld: error: undefined symbol: wcslen * * Restart config... * * * General architecture-dependent options * Kprobes (KPROBES) [N/y/?] n Optimize very unlikely/likely branches (JUMP_LABEL) [Y/n/?] y Static key selftest (STATIC_KEYS_SELFTEST) [N/y/?] n Static call selftest (STATIC_CALL_SELFTEST) [N/y/?] n Enable seccomp to safely execute untrusted bytecode (SECCOMP) [Y/n/?] y Show seccomp filter cache status in /proc/pid/seccomp_cache (SECCOMP_CACHE_DEBUG) [N/y/?] n Stack Protector buffer overflow detection (STACKPROTECTOR) [Y/n/?] y Strong Stack Protector (STACKPROTECTOR_STRONG) [Y/n/?] y Link Time Optimization (LTO) > 1. None (LTO_NONE) choice[1]: 1 Use Clang's Control Flow Integrity (CFI) (CFI_CLANG) [N/y/?] (NEW) Error in reading or end of file. Number of bits to use for ASLR of mmap base address (ARCH_MMAP_RND_BITS) [28] 28 Number of bits to use for ASLR of mmap base address for compatible applications (ARCH_MMAP_RND_COMPAT_BITS) [8] 8 MMU page size > 1. 4KiB pages (PAGE_SIZE_4KB) choice[1]: 1 Provide system calls for 32-bit time_t (COMPAT_32BIT_TIME) [Y/n/?] y Use a virtually-mapped stack (VMAP_STACK) [Y/n/?] y Support for randomizing kernel stack offset on syscall entry (RANDOMIZE_KSTACK_OFFSET) [Y/n/?] y Default state of kernel stack offset randomization (RANDOMIZE_KSTACK_OFFSET_DEFAULT) [N/y/?] n Locking event counts collection (LOCK_EVENT_COUNTS) [N/y/?] n * * Memory initialization * Initialize kernel stack variables at function entry 1. no automatic stack variable initialization (weakest) (INIT_STACK_NONE) 2. pattern-init everything (strongest) (INIT_STACK_ALL_PATTERN) > 3. zero-init everything (strongest and safest) (INIT_STACK_ALL_ZERO) choice[1-3?]: 3 Enable heap memory zeroing on allocation by default (INIT_ON_ALLOC_DEFAULT_ON) [Y/n/?] y Enable heap memory zeroing on free by default (INIT_ON_FREE_DEFAULT_ON) [N/y/?] n Enable register zeroing on function exit (ZERO_CALL_USED_REGS) [N/y/?] (NEW) Error in reading or end of file. * * Kernel hardening options * Randomize layout of sensitive kernel structures > 1. Disable structure layout randomization (RANDSTRUCT_NONE) 2. Fully randomize structure layout (RANDSTRUCT_FULL) (NEW) choice[1-2?]: Error in reading or end of file. * * Compile-time checks and compiler options * Debug information 1. Disable debug information (DEBUG_INFO_NONE) 2. Rely on the toolchain's implicit default DWARF version (DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT) > 3. Generate DWARF Version 4 debuginfo (DEBUG_INFO_DWARF4) 4. Generate DWARF Version 5 debuginfo (DEBUG_INFO_DWARF5) choice[1-4?]: 3 Reduce debugging information (DEBUG_INFO_REDUCED) [N/y/?] n Compressed Debug information > 1. Don't compress debug information (DEBUG_INFO_COMPRESSED_NONE) 2. Compress debugging information with zlib (DEBUG_INFO_COMPRESSED_ZLIB) 3. Compress debugging information with zstd (DEBUG_INFO_COMPRESSED_ZSTD) (NEW) choice[1-3?]: Error in reading or end of file. Produce split debuginfo in .dwo files (DEBUG_INFO_SPLIT) [N/y/?] n Generate BTF type information (DEBUG_INFO_BTF) [N/y/?] n Provide GDB scripts for kernel debugging (GDB_SCRIPTS) [N/y/?] n Warn for stack frames larger than (FRAME_WARN) [2048] 2048 Strip assembler-generated symbols during link (STRIP_ASM_SYMS) [N/y/?] n Install uapi headers to usr/include (HEADERS_INSTALL) [N/y/?] n Make section mismatch errors non-fatal (SECTION_MISMATCH_WARN_ONLY) [Y/n/?] y Force all function address 64B aligned (DEBUG_FORCE_FUNCTION_ALIGN_64B) [N/y/?] n Generate vmlinux.map file when linking (VMLINUX_MAP) [N/y/?] n Force weak per-cpu definitions (DEBUG_FORCE_WEAK_PER_CPU) [N/y/?] n In file included from /app/workdir/cache/src/203b599a016d2a493034b4ba841e89a3c364a65a/io_uring/io_uring.c:96: In file included from /app/workdir/cache/src/203b599a016d2a493034b4ba8
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: kernel BUG in jfs_unlink (log)
Repro: C syz .config
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (2)
Title Replies (including bot) Last reply
[PATCH] VFS: check i_nlink count before trying to unlink 2 (2) 2024/09/07 19:02
[syzbot] [jfs?] kernel BUG in jfs_unlink 0 (3) 2024/09/07 16:48
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 kernel BUG in jfs_unlink origin:upstream -1 C error 1 86d 86d 0/2 upstream: reported C repro on 2026/02/22 02:11
linux-5.15 kernel BUG in jfs_unlink -1 1 323d 323d 0/3 auto-obsoleted due to no activity on 2025/10/07 19:02
linux-6.1 kernel BUG in jfs_unlink -1 C 1 23d 23d 0/3 upstream: reported C repro on 2026/04/26 03:49
▶ ▼ Last patch testing requests (11)
Created Duration User Patch Repo Result
2026/05/19 02:03 40m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci OK log
2026/05/18 21:22 3h16m retest repro linux-next log
2026/05/18 21:20 3h06m retest repro linux-next log
2026/04/02 01:49 13m retest repro upstream report log
2026/03/09 20:46 17m retest repro linux-next report log
2026/03/09 19:09 1h22m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2025/12/23 00:06 21m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/11/07 06:22 13m retest repro upstream report log
2025/10/03 01:02 40m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/07/24 18:39 18m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2024/09/07 16:48 20m ghanshyam1898@gmail.com patch upstream OK log
▶ ▼ Fix bisection attempts (11)
Created Duration User Patch Repo Result
2026/01/22 01:34 2m bisect fix upstream error job log
2025/12/08 21:55 1h50m bisect fix upstream OK (0) job log log
2025/08/28 04:12 2h18m bisect fix upstream OK (0) job log log
2025/06/25 01:34 1h57m bisect fix upstream OK (0) job log log
2025/05/25 10:14 2h46m bisect fix upstream OK (0) job log log
2025/04/22 05:17 3h42m bisect fix upstream OK (0) job log log
2025/03/19 15:28 3h31m bisect fix upstream OK (0) job log log
2025/02/16 12:34 1h30m bisect fix upstream OK (0) job log log
2025/01/16 20:33 1h56m bisect fix upstream OK (0) job log log
2024/11/30 12:57 2h16m bisect fix upstream OK (0) job log log
2024/10/16 22:37 2h20m bisect fix upstream OK (0) job log log

Sample crash report:
BUG at fs/jfs/namei.c:513 assert(ip->i_nlink)
------------[ cut here ]------------
kernel BUG at fs/jfs/namei.c:513!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 5224 Comm: syz-executor204 Not tainted 6.11.0-rc6-syzkaller-00017-gc9f016e72b5c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
RIP: 0010:jfs_unlink+0xafd/0xb30 fs/jfs/namei.c:513
Code: e8 c8 5d 91 08 e8 83 f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba 01 02 00 00 48 c7 c1 60 9c 22 8c e8 64 5e 8e 08 90 <0f> 0b e8 5c f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba
RSP: 0018:ffffc9000344fbe0 EFLAGS: 00010246
RAX: 000000000000002d RBX: 0000000000000000 RCX: 44cfc770ad800100
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000344fd10 R08: ffffffff8174016c R09: 1ffff92000689f1c
R10: dffffc0000000000 R11: fffff52000689f1d R12: 0000000000000000
R13: ffffc9000344fc60 R14: 1ffff92000689f8c R15: ffff888072c33248
FS:  0000555577bcd380(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 000000007ab8a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 vfs_unlink+0x365/0x650 fs/namei.c:4422
 do_unlinkat+0x4ae/0x830 fs/namei.c:4486
 __do_sys_unlink fs/namei.c:4534 [inline]
 __se_sys_unlink fs/namei.c:4532 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4532
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f69ef25fad7
Code: 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff4544dac8 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f69ef25fad7
RDX: 00007fff4544daf0 RSI: 00007fff4544db80 RDI: 00007fff4544db80
RBP: 00007fff4544db80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007fff4544ec70
R13: 0000555577bd6700 R14: 0000000000000001 R15: 431bde82d7b634db
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:jfs_unlink+0xafd/0xb30 fs/jfs/namei.c:513
Code: e8 c8 5d 91 08 e8 83 f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba 01 02 00 00 48 c7 c1 60 9c 22 8c e8 64 5e 8e 08 90 <0f> 0b e8 5c f0 73 fe 48 c7 c7 20 9c 22 8c 48 c7 c6 e0 99 22 8c ba
RSP: 0018:ffffc9000344fbe0 EFLAGS: 00010246
RAX: 000000000000002d RBX: 0000000000000000 RCX: 44cfc770ad800100
RDX: 0000000000000000 RSI: 0000000080000000 RDI: 0000000000000000
RBP: ffffc9000344fd10 R08: ffffffff8174016c R09: 1ffff92000689f1c
R10: dffffc0000000000 R11: fffff52000689f1d R12: 0000000000000000
R13: ffffc9000344fc60 R14: 1ffff92000689f8c R15: ffff888072c33248
FS:  0000555577bcd380(0000) GS:ffff8880b8900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000045bdd0 CR3: 000000007ab8a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

Crashes (23):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/09/02 11:32 upstream c9f016e72b5c 1eda0d14 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs kernel BUG in jfs_unlink
2026/02/23 17:49 linux-next d4906ae14a5f 305c0ec5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-linux-next-kasan-gce-root kernel BUG in jfs_unlink
2026/05/02 16:02 upstream f1a5e78a55eb a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in jfs_unlink
2026/05/01 14:34 upstream 26fd6bff2c05 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in jfs_unlink
2025/08/30 20:49 upstream 11e7861d680c 807a3b61 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in jfs_unlink
2024/09/02 10:40 upstream c9f016e72b5c 1eda0d14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in jfs_unlink
2024/07/21 22:43 upstream 2c9b3512402e b88348e9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs kernel BUG in jfs_unlink
2025/07/10 15:45 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci ec4801305969 19d4829f .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:56 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:55 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:54 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:54 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:54 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:54 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:53 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:52 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:52 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:52 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:50 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:50 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:50 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:50 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
2024/08/15 23:50 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci 7c626ce4bae1 e4bacdaf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 kernel BUG in jfs_unlink
* Struck through repros no longer work on HEAD.