syzbot


UBSAN: shift-out-of-bounds in ext4_check_opt_consistency

Status: upstream: reported C repro on 2026/04/19 15:50
Reported-by: syzbot+943e137a1dc67bf6c5c7@syzkaller.appspotmail.com
First crash: 2d19h, last: 2d17h
Bug presence (1)
Date Name Commit Repro Result
2026/04/19 upstream (ToT) bea8d77e45a8 C Failed due to an error; will retry later
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 UBSAN: shift-out-of-bounds in ext4_check_opt_consistency origin:lts -1 C error 6 3d13h 107d 0/2 upstream: reported C repro on 2026/01/05 06:19

Sample crash report:
EXT4-fs error (device loop0) in ext4_process_orphan:345: Corrupt filesystem
EXT4-fs (loop0): 1 truncate cleaned up
EXT4-fs (loop0): mounted filesystem without journal. Quota mode: writeback.
================================================================================
UBSAN: shift-out-of-bounds in fs/ext4/super.c:2766:15
shift exponent 1987084706 is too large for 32-bit type 'int'
CPU: 0 PID: 4479 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c 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+0x2b0/0x348 lib/ubsan.c:321
 ext4_check_opt_consistency+0x16d0/0x1afc fs/ext4/super.c:2766
 ext4_reconfigure+0xac/0x2268 fs/ext4/super.c:6694
 reconfigure_super+0x1d4/0x79c fs/super.c:977
 do_remount fs/namespace.c:2741 [inline]
 path_mount+0xbdc/0xe80 fs/namespace.c:3400
 do_mount fs/namespace.c:3421 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount fs/namespace.c:3606 [inline]
 __arm64_sys_mount+0x49c/0x59c fs/namespace.c:3606
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
================================================================================
EXT4-fs: test_dummy_encryption requires encrypt feature

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/19 17:53 linux-6.1.y 7c87defbd336 303e2802 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] [mounted in repro #3 (clean fs)] ci2-linux-6-1-kasan-arm64 UBSAN: shift-out-of-bounds in ext4_check_opt_consistency
2026/04/19 17:13 linux-6.1.y 7c87defbd336 303e2802 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] [mounted in repro #3 (clean fs)] ci2-linux-6-1-kasan-arm64 UBSAN: shift-out-of-bounds in ext4_check_opt_consistency
2026/04/19 16:32 linux-6.1.y 7c87defbd336 303e2802 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] [mounted in repro #3 (clean fs)] ci2-linux-6-1-kasan-arm64 UBSAN: shift-out-of-bounds in ext4_check_opt_consistency
2026/04/19 15:50 linux-6.1.y 7c87defbd336 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 UBSAN: shift-out-of-bounds in ext4_check_opt_consistency
* Struck through repros no longer work on HEAD.