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KASAN: slab-out-of-bounds Read in ext4_search_dir

Status: upstream: reported C repro on 2023/11/17 09:38
Reported-by: syzbot+ac107c9fba66d9b8ad08@syzkaller.appspotmail.com
First crash: 947d, last: 14h02m
Fix bisection: failed (error log, bisect log)
  
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: slab-out-of-bounds Read in ext4_search_dir origin:upstream missing-backport 19 C done 6 588d 947d 0/2 auto-obsoleted due to no activity on 2025/02/18 18:03
upstream KASAN: use-after-free Read in ext4_search_dir prio:low ext4 19 C error done 20 896d 1137d 25/29 fixed on 2024/02/21 18:23
upstream KASAN: slab-out-of-bounds Read in ext4_search_dir ext4 19 C 5 179d 262d 29/29 fixed on 2026/05/06 16:40
linux-5.15 KASAN: use-after-free Read in ext4_search_dir 19 C done 5 623d 1101d 3/3 fixed on 2024/11/08 17:20
android-54 KASAN: use-after-free Read in ext4_search_dir 19 C 17 628d 797d 0/2 auto-obsoleted due to no activity on 2025/02/18 14:16
android-6-1 KASAN: use-after-free Read in ext4_search_dir missing-backport origin:upstream 19 C error error 29 153d 973d 0/2 upstream: reported C repro on 2023/10/22 16:55
android-5-15 KASAN: use-after-free Read in ext4_search_dir 19 C 4 15h00m 15h39m 0/2 upstream: reported C repro on 2026/06/21 07:51
linux-6.1 KASAN: use-after-free Read in ext4_search_dir origin:upstream missing-backport 19 C done 1 638d 1099d 0/3 upstream: reported C repro on 2023/06/18 19:29
upstream KASAN: use-after-free Read in ext4_search_dir (2) ext4 19 C 5 647d 671d 28/29 fixed on 2024/10/22 11:57
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/06/14 21:23 13m retest repro android13-5.10-lts log
2026/06/14 21:23 26m retest repro android13-5.10-lts log
2026/06/14 21:23 42m retest repro android13-5.10-lts log
2026/04/05 13:32 6m retest repro android13-5.10-lts report log
2026/04/05 13:32 33m retest repro android13-5.10-lts report log
2026/04/05 13:32 31m retest repro android13-5.10-lts report log
2026/01/25 12:00 6m retest repro android13-5.10-lts report log
2026/01/25 12:00 8m retest repro android13-5.10-lts report log
2026/01/25 12:00 5m retest repro android13-5.10-lts report log
2025/11/16 10:02 7m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (5)
Created Duration User Patch Repo Result
2024/05/30 18:28 6m bisect fix android13-5.10-lts error job log
2024/04/06 20:03 1h02m bisect fix android13-5.10-lts OK (0) job log log
2024/03/06 22:56 37m bisect fix android13-5.10-lts OK (0) job log log
2024/02/03 06:35 36m bisect fix android13-5.10-lts OK (0) job log log
2023/12/31 11:12 35m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
EXT4-fs: Warning: mounting with data=journal disables delayed allocation, dioread_nolock, O_DIRECT and fast_commit support!
EXT4-fs (loop2): encrypted files will use data=ordered instead of data journaling mode
EXT4-fs (loop2): 1 truncate cleaned up
EXT4-fs (loop2): mounted filesystem without journal. Opts: noblock_validity,max_batch_time=0x0000000000000002,resuid=0x0000000000000000,block_validity,stripe=0x0000000000000009,nombcache,,errors=continue
==================================================================
BUG: KASAN: use-after-free in ext4_search_dir+0xf8/0x1c0 fs/ext4/namei.c:1516
Read of size 1 at addr ffff88812752cc86 by task syz.2.17/382

CPU: 0 PID: 382 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 ext4_search_dir+0xf8/0x1c0 fs/ext4/namei.c:1516
 ext4_find_inline_entry+0x4f2/0x630 fs/ext4/inline.c:1730
 __ext4_find_entry+0x2fa/0x1930 fs/ext4/namei.c:1589
 ext4_lookup_entry fs/ext4/namei.c:1746 [inline]
 ext4_lookup+0x305/0x8c0 fs/ext4/namei.c:1814
 __lookup_hash+0x114/0x250 fs/namei.c:1549
 filename_create+0x1d7/0x680 fs/namei.c:3616
 user_path_create fs/namei.c:3673 [inline]
 do_mkdirat+0x5e/0x340 fs/namei.c:3813
 __do_sys_mkdirat fs/namei.c:3831 [inline]
 __se_sys_mkdirat fs/namei.c:3829 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3829
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7efc7c657cc7
Code: 00 66 90 48 89 f2 b9 00 01 00 00 48 89 fe bf 9c ff ff ff e9 db f7 ff ff 66 2e 0f 1f 84 00 00 00 00 00 90 b8 02 01 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007efc7c4bae58 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007efc7c4baee0 RCX: 00007efc7c657cc7
RDX: 00000000000001ff RSI: 0000200000000080 RDI: 00000000ffffff9c
RBP: 0000200000000140 R08: 0000200000000080 R09: 0000000000000000
R10: 0000200000000140 R11: 0000000000000246 R12: 0000200000000080
R13: 00007efc7c4baea0 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea00049d4b00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12752c
flags: 0x4000000000000000()
raw: 4000000000000000 ffffea00049717c8 ffffea0004975448 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x100cca(GFP_HIGHUSER_MOVABLE), pid 360, ts 29109276013, free_ts 29356072505
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 __alloc_pages include/linux/gfp.h:544 [inline]
 __alloc_pages_node include/linux/gfp.h:557 [inline]
 alloc_pages_node include/linux/gfp.h:571 [inline]
 alloc_pages include/linux/gfp.h:590 [inline]
 do_cow_fault mm/memory.c:4427 [inline]
 do_fault mm/memory.c:4538 [inline]
 handle_pte_fault+0x1050/0x3910 mm/memory.c:4800
 __handle_mm_fault mm/memory.c:4953 [inline]
 handle_mm_fault+0xf86/0x1720 mm/memory.c:5367
 do_user_addr_fault+0x576/0xe20 arch/x86/mm/fault.c:1343
 handle_page_fault arch/x86/mm/fault.c:1436 [inline]
 exc_page_fault+0x5a/0xc0 arch/x86/mm/fault.c:1492
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:571
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 free_pcp_prepare mm/page_alloc.c:1421 [inline]
 free_unref_page_prepare+0x2b7/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x129/0x9c0 mm/page_alloc.c:3443
 release_pages+0xe41/0xe90 mm/swap.c:1103
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:356
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x17e/0x310 mm/mmu_gather.c:326
 exit_mmap+0x329/0x590 mm/mmap.c:3387
 __mmput+0x92/0x2d0 kernel/fork.c:1153
 mmput+0x4e/0x150 kernel/fork.c:1176
 exit_mm kernel/exit.c:540 [inline]
 do_exit+0x9d8/0x24e0 kernel/exit.c:860
 do_group_exit+0x149/0x310 kernel/exit.c:987
 get_signal+0xfb1/0x1300 kernel/signal.c:2793
 arch_do_signal_or_restart+0xe7/0x11b0 arch/x86/kernel/signal.c:805
 handle_signal_work kernel/entry/common.c:145 [inline]
 exit_to_user_mode_loop+0xa2/0xe0 kernel/entry/common.c:169
 exit_to_user_mode_prepare+0x76/0xa0 kernel/entry/common.c:199
 syscall_exit_to_user_mode+0x1d/0x40 kernel/entry/common.c:274
 do_syscall_64+0x3d/0x40 arch/x86/entry/common.c:56

Memory state around the buggy address:
 ffff88812752cb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812752cc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812752cc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88812752cd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812752cd80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (24):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/21 09:02 android13-5.10-lts 6321e6c974f1 43bfcdb0 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/18 12:48 android13-5.10-lts e5e5644ea27f 666f77ed .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/18 12:06 android13-5.10-lts e5e5644ea27f 666f77ed .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/18 11:44 android13-5.10-lts e5e5644ea27f 666f77ed .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2026/06/21 09:28 android13-5.10-lts 6321e6c974f1 43bfcdb0 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2026/06/21 08:40 android13-5.10-lts 6321e6c974f1 43bfcdb0 .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/27 11:18 android13-5.10-lts e5e5644ea27f 65e8686b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_search_dir
2024/10/05 18:34 android13-5.10-lts e5e5644ea27f d7906eff .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_search_dir
2023/11/17 09:36 android13-5.10-lts d30b996835c0 cb976f63 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_search_dir
2024/11/15 14:25 android13-5.10-lts 6a01908517df f6ede3a3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/11/01 06:55 android13-5.10-lts e5e5644ea27f 96eb609f .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/30 20:11 android13-5.10-lts e5e5644ea27f fb888278 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/27 15:46 android13-5.10-lts e5e5644ea27f 65e8686b .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/27 05:13 android13-5.10-lts e5e5644ea27f 65e8686b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/27 04:15 android13-5.10-lts e5e5644ea27f 65e8686b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/27 03:07 android13-5.10-lts e5e5644ea27f 65e8686b .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/08 00:14 android13-5.10-lts e5e5644ea27f d7906eff .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/05 18:58 android13-5.10-lts e5e5644ea27f d7906eff .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/10/05 18:12 android13-5.10-lts e5e5644ea27f d7906eff .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/09/10 21:33 android13-5.10-lts 1c5354a314ea 86aa7bd7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/09/02 00:25 android13-5.10-lts 1c5354a314ea 1eda0d14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/07/25 06:41 android13-5.10-lts fd58936f3c1f d1a1b0ca .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/07/25 06:11 android13-5.10-lts fd58936f3c1f d1a1b0ca .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
2024/04/15 07:06 android13-5.10-lts 4e1bc8d8e8ae c8349e48 .config strace log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_search_dir
* Struck through repros no longer work on HEAD.