UBSAN: shift-out-of-bounds in extAlloc (2)

Status: upstream: reported C repro on 2025/05/14 03:45
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+fd9bfadbf8265184a6b7@syzkaller.appspotmail.com
First crash: 454d, last: 24d
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2025/05/14 upstream (ToT) 1a80a098c606 C [report] UBSAN: shift-out-of-bounds in extAlloc
▶ ▼ Similar bugs (5)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream UBSAN: shift-out-of-bounds in extAlloc jfs -1 syz, C error 6605 1055d 1415d 23/29 fixed on 2023/10/12 12:47
linux-6.6 UBSAN: shift-out-of-bounds in extAlloc -1 1 215d 215d 0/2 auto-obsoleted due to no activity on 2026/04/18 15:14
linux-5.15 UBSAN: shift-out-of-bounds in extAlloc origin:upstream -1 syz, C done 217 1059d 1251d 3/3 fixed on 2023/10/20 00:28
linux-6.1 UBSAN: shift-out-of-bounds in extAlloc origin:upstream missing-backport -1 syz, C done 204 483d 1247d 3/3 fixed on 2025/05/02 07:04
upstream UBSAN: shift-out-of-bounds in extAlloc (2) prio:high jfs -1 syz, C inconclusive 13 28d 830d 0/29 upstream: reported C repro on 2024/05/03 13:40
▶ ▼ Last patch testing requests (6)
Created Duration User Patch Repo Result
2026/07/18 12:59 16m retest repro linux-5.15.y report log
2026/04/06 12:18 10m retest repro linux-5.15.y report log
2026/01/26 06:48 16m retest repro linux-5.15.y report log
2025/11/17 05:37 14m retest repro linux-5.15.y report log
2025/09/07 08:34 10m retest repro linux-5.15.y report log
2025/05/28 19:10 11m retest repro linux-5.15.y report log

Sample crash report:
loop0: detected capacity change from 0 to 32768
================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_extent.c:516:16
shift exponent 108 is too large for 64-bit type 's64' (aka 'long long')
CPU: 0 PID: 4022 Comm: syz-executor958 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 ubsan_epilogue+0x14/0x48 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x2b4/0x358 lib/ubsan.c:321
 extBalloc fs/jfs/jfs_extent.c:516 [inline]
 extAlloc+0xaa8/0xdc4 fs/jfs/jfs_extent.c:125
 jfs_get_block+0x2bc/0x8ec fs/jfs/inode.c:258
 nobh_write_begin+0x2d8/0x9d4 fs/buffer.c:2650
 jfs_write_begin+0x58/0xa0 fs/jfs/inode.c:322
 generic_perform_write+0x204/0x480 mm/filemap.c:3785
 __generic_file_write_iter+0x23c/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb0/0x1b4 mm/filemap.c:3944
 call_write_iter include/linux/fs.h:2172 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7c8/0xa2c fs/read_write.c:594
 ksys_write+0x120/0x210 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
================================================================================
================================================================================
UBSAN: shift-out-of-bounds in fs/jfs/jfs_dmap.c:2716:11
shift exponent 94 is too large for 32-bit type 'int'
CPU: 0 PID: 4022 Comm: syz-executor958 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
Call trace:
 dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106
 dump_stack+0x1c/0x5c lib/dump_stack.c:113
 ubsan_epilogue+0x14/0x48 lib/ubsan.c:151
 __ubsan_handle_shift_out_of_bounds+0x2b4/0x358 lib/ubsan.c:321
 dbSplit+0x1d4/0x1d8 fs/jfs/jfs_dmap.c:2716
 dbAdjCtl+0x2bc/0x8c8 fs/jfs/jfs_dmap.c:2608
 dbAllocDmap+0xb0/0x128 fs/jfs/jfs_dmap.c:2119
 dbAllocNext+0x35c/0x3a0 fs/jfs/jfs_dmap.c:1254
 dbAlloc+0x334/0x978 fs/jfs/jfs_dmap.c:820
 extBalloc fs/jfs/jfs_extent.c:523 [inline]
 extAlloc+0x3f4/0xdc4 fs/jfs/jfs_extent.c:125
 jfs_get_block+0x2bc/0x8ec fs/jfs/inode.c:258
 nobh_write_begin+0x2d8/0x9d4 fs/buffer.c:2650
 jfs_write_begin+0x58/0xa0 fs/jfs/inode.c:322
 generic_perform_write+0x204/0x480 mm/filemap.c:3785
 __generic_file_write_iter+0x23c/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb0/0x1b4 mm/filemap.c:3944
 call_write_iter include/linux/fs.h:2172 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7c8/0xa2c fs/read_write.c:594
 ksys_write+0x120/0x210 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
================================================================================
------------[ cut here ]------------
WARNING: CPU: 0 PID: 4022 at fs/jfs/jfs_dmap.c:2950 dbAdjTree+0x3a8/0x414 fs/jfs/jfs_dmap.c:2950
Modules linked in:
CPU: 0 PID: 4022 Comm: syz-executor958 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : dbAdjTree+0x3a8/0x414 fs/jfs/jfs_dmap.c:2950
lr : dbAdjTree+0x3a8/0x414 fs/jfs/jfs_dmap.c:2950
sp : ffff80001cf971f0
x29: ffff80001cf97200 x28: dfff800000000000 x27: ffff0000d5754011
x26: 000000000000005e x25: ffff0000d5754000 x24: 0000000040000155
x23: ffff0000d5754008 x22: 0000000000000555 x21: 0000000040000000
x20: 000000000000006b x19: dfff800000000000 x18: 0000000000000001
x17: 0000000000000000 x16: ffff8000081844d8 x15: 00000000ffffffff
x14: 0000000000ff0100 x13: 0000000000000001 x12: 0000000000ff0100
x11: 0000000000000000 x10: 0000000000000000 x9 : ffff8000097a9dec
x8 : ffff0000c2718000 x7 : 0000000000000001 x6 : 0000000000000001
x5 : ffff80001cf96a98 x4 : ffff80001422f280 x3 : 0000000000000001
x2 : 000000000000006b x1 : 0000000000000555 x0 : 0000000040000155
Call trace:
 dbAdjTree+0x3a8/0x414 fs/jfs/jfs_dmap.c:2950
 dbSplit+0x10c/0x1d8 fs/jfs/jfs_dmap.c:2723
 dbAdjCtl+0x2bc/0x8c8 fs/jfs/jfs_dmap.c:2608
 dbAllocDmap+0xb0/0x128 fs/jfs/jfs_dmap.c:2119
 dbAllocNext+0x35c/0x3a0 fs/jfs/jfs_dmap.c:1254
 dbAlloc+0x334/0x978 fs/jfs/jfs_dmap.c:820
 extBalloc fs/jfs/jfs_extent.c:523 [inline]
 extAlloc+0x3f4/0xdc4 fs/jfs/jfs_extent.c:125
 jfs_get_block+0x2bc/0x8ec fs/jfs/inode.c:258
 nobh_write_begin+0x2d8/0x9d4 fs/buffer.c:2650
 jfs_write_begin+0x58/0xa0 fs/jfs/inode.c:322
 generic_perform_write+0x204/0x480 mm/filemap.c:3785
 __generic_file_write_iter+0x23c/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb0/0x1b4 mm/filemap.c:3944
 call_write_iter include/linux/fs.h:2172 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x7c8/0xa2c fs/read_write.c:594
 ksys_write+0x120/0x210 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:656
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584
irq event stamp: 106784
hardirqs last  enabled at (106783): [<ffff8000082f7640>] __up_console_sem+0xb4/0x100 kernel/printk/printk.c:257
hardirqs last disabled at (106784): [<ffff8000111a0cd0>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:396
softirqs last  enabled at (106768): [<ffff80000819d0d8>] softirq_handle_end kernel/softirq.c:401 [inline]
softirqs last  enabled at (106768): [<ffff80000819d0d8>] handle_softirqs+0xa4c/0xbf0 kernel/softirq.c:586
softirqs last disabled at (106751): [<ffff80000819d6dc>] __do_softirq kernel/softirq.c:592 [inline]
softirqs last disabled at (106751): [<ffff80000819d6dc>] do_softirq_own_stack include/asm-generic/softirq_stack.h:10 [inline]
softirqs last disabled at (106751): [<ffff80000819d6dc>] invoke_softirq kernel/softirq.c:439 [inline]
softirqs last disabled at (106751): [<ffff80000819d6dc>] __irq_exit_rcu+0x240/0x440 kernel/softirq.c:641
---[ end trace b9cf5642d8deefa6 ]---
JFS: block map error in dbBackSplit

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/14 03:44 linux-5.15.y 3b8db0e4f263 7344edeb .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-linux-5-15-kasan-arm64 UBSAN: shift-out-of-bounds in extAlloc
* Struck through repros no longer work on HEAD.