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UBSAN: shift-out-of-bounds in dbAllocAG (3)

Status: upstream: reported C repro on 2025/10/17 04:35
Subsystems: jfs
[Documentation on labels]
Reported-by: syzbot+4b717071f1eecb2972df@syzkaller.appspotmail.com
First crash: 222d, last: 128d
Cause bisection: failed (error log, bisect log)
  
Fix bisection: failed (error log, bisect log)
  
▶ ▼ ✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
c0f56205-875d-4ec0-8ba6-1cb39e6ccfbb assessment-security 💥 UBSAN: shift-out-of-bounds in dbAllocAG (3) 2026/05/21 15:45 2026/05/21 15:45 2026/05/21 15:48 d57425845dbe663f86e1e54a4997e95bd557b624 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/ab0d0f43a7a9febdf514e54cfba469fd1bdc421a" "-s" "bzImage" "compile_commands.json"]: exit status 2 Root cause: error: mixing `-Zsanitizer` will cause an ABI mismatch in crate `build_error` error: aborting due to 2 previous errors * * Restart config... * * * 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 Poison kernel stack before returning from syscalls (KSTACK_ERASE) [N/y/?] (NEW) Error in reading or end of file. 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/?] n error: mixing `-Zsanitizer` will cause an ABI mismatch in crate `build_error` --> /app/workdir/cache/src/609a9c78b1407297cea283ac4696859ef928b2a3/rust/build_error.rs:3:1 | 3 | //! Build-time error. | ^ | = help: the `-Zsanitizer` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely = note: unset `-Zsanitizer` in this crate is incompatible with `-Zsanitizer=kernel-address` in dependency `core` = help: set `-Zsanitizer=kernel-address` in this crate or unset `-Zsanitizer` in `core` = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=sanitizer` to silence this error error: mixing `-Zsanitizer` will cause an ABI mismatch in crate `build_error` --> /app/workdir/cache/src/609a9c78b1407297cea283ac4696859ef928b2a3/rust/build_error.rs:3:1 | 3 | //! Build-time error. | ^ | = help: the `-Zsanitizer` flag modifies the ABI so Rust crates compiled with different values of this flag cannot be used together safely = note: unset `-Zsanitizer` in this crate is incompatible with `-Zsanitizer=kernel-address` in dependency `compiler_builtins` = help: set `-Zsanitizer=kernel-address` in this crate or unset `-Zsanitizer` in `compiler_builtins` = help: if you are sure this will not cause problems, you may use `-Cunsafe-allow-abi-mismatch=sanitizer` to silence this error error: aborting due to 2 previous errors make[3]: *** [/app/workdir/cache/src/609a9c78b1407297cea283ac4696859ef928b2a3/rust/Makefile:527: rust/build_error.o] Error 1 make[3]: *** Waiting for unfinished jobs.... make[2]: *** [/app/workdir/cache/src/609a9c78b1407297cea283ac4696859ef928b2a3/Makefile:1286: prepare] Error 2 make[1]: *** [/app/workdir/cache/src/609a9c78b1407297cea283ac4696859ef928b2a3/Makefile:248: __sub-make] Error 2 make: *** [Makefile:248: __sub-make] Error 2
▶ ▼ Discussions (3)
Title Replies (including bot) Last reply
[syzbot] [jfs?] UBSAN: shift-out-of-bounds in dbAllocAG (3) 0 (5) 2026/04/17 16:20
[PATCH] jfs: validate budmin to prevent shift-out-of-bounds in dbAllocAG() 4 (4) 2025/10/22 13:22
[PATCH] jfs: test syz test 1 (2) 2025/10/17 10:52
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream UBSAN: shift-out-of-bounds in dbAllocAG (2) jfs -1 C done 5 394d 444d 29/29 fixed on 2025/07/08 00:33
upstream UBSAN: shift-out-of-bounds in dbAllocAG jfs -1 C error 10 1303d 1335d 22/29 fixed on 2023/02/24 13:50
▶ ▼ Last patch testing requests (15)
Created Duration User Patch Repo Result
2026/05/10 04:37 20m retest repro upstream report log
2026/04/17 16:20 18m tristmd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master report log
2026/04/17 10:12 5m tristmd@gmail.com patch https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master error
2026/03/28 13:23 39m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/03/28 13:23 25m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/03/28 11:36 39m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/03/28 11:36 25m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/03/28 08:40 24m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci error
2026/01/17 06:45 23m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/01/17 06:45 33m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/01/17 06:45 32m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2026/01/17 06:45 1h05m retest repro git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci report log
2025/10/17 20:13 23m hsukrut3@gmail.com patch upstream OK log
2025/10/17 19:25 9m hsukrut3@gmail.com patch upstream error
2025/10/17 08:24 1h41m xiaopei01@kylinos.cn patch upstream report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/02/16 12:21 1m bisect fix upstream error job log
2026/01/03 04:15 1h46m bisect fix upstream OK (0) job log log
2025/12/01 15:34 2h36m bisect fix upstream OK (0) job log log

Sample crash report:
------------[ cut here ]------------
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:1440:48
shift exponent -1 is negative
CPU: 0 UID: 0 PID: 6076 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:233
 __ubsan_handle_shift_out_of_bounds+0x386/0x410 lib/ubsan.c:494
 dbAllocAG+0xfc0/0xff0 fs/jfs/jfs_dmap.c:1440
 dbAlloc+0x5a8/0xba0 fs/jfs/jfs_dmap.c:877
 extBalloc fs/jfs/jfs_extent.c:336 [inline]
 extAlloc+0x54a/0xfb0 fs/jfs/jfs_extent.c:127
 jfs_get_block+0x346/0xab0 fs/jfs/inode.c:254
 __block_write_begin_int+0x6b5/0x1900 fs/buffer.c:2145
 block_write_begin+0x8a/0x120 fs/buffer.c:2256
 jfs_write_begin+0x35/0x80 fs/jfs/inode.c:306
 generic_perform_write+0x29d/0x8c0 mm/filemap.c:4242
 generic_file_write_iter+0x118/0x550 mm/filemap.c:4385
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5d5/0xb40 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa99272eec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffa62c1048 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fa992985fa0 RCX: 00007fa99272eec9
RDX: 0000000000000014 RSI: 0000200000000380 RDI: 0000000000000005
RBP: 00007fa9927b1f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa992985fa0 R14: 00007fa992985fa0 R15: 0000000000000003
 </TASK>
---[ end trace ]---

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/16 16:27 upstream 7ea30958b305 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-upstream-fs UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 15:28 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 14:31 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 13:24 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 12:23 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 11:25 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
2025/10/16 10:11 git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci bf45a62baffc 19568248 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-gce-arm64 UBSAN: shift-out-of-bounds in dbAllocAG
* Struck through repros no longer work on HEAD.