syzbot

 sign-in | mailing list | source | docs
🐞 Open [124]
🐞 Fixed [70]
🐞 Invalid [216]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

KASAN: use-after-free Write in ext4_insert_dentry

Status: upstream: reported C repro on 2024/09/14 11:48
Reported-by: syzbot+5371fd14aab16dddac77@syzkaller.appspotmail.com
First crash: 274d, last: 55d
Fix bisection: fixed by (bisect log) :
commit 515c34cff899eb5dae6aa7eee01c1295b07d81af
Author: Artem Sadovnikov <a.sadovnikov@ispras.ru>
Date: Fri Apr 4 08:28:05 2025 +0000

  ext4: fix off-by-one error in do_split

  
▶ ▼ Similar bugs (5)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Write in ext4_insert_dentry missing-backport C done 10 46d 231d 0/2 upstream: reported C repro on 2024/10/27 00:37
android-6-1 KASAN: use-after-free Write in ext4_insert_dentry missing-backport origin:upstream C 12 22d 197d 0/2 upstream: reported C repro on 2024/11/30 15:43
android-54 KASAN: use-after-free Write in ext4_insert_dentry C 7 41d 70d 0/2 upstream: reported C repro on 2025/04/06 12:10
linux-5.15 KASAN: use-after-free Write in ext4_insert_dentry origin:upstream C done 4 47d 198d 3/3 fixed on 2025/06/02 10:49
upstream KASAN: use-after-free Write in ext4_insert_dentry ext4 C done 117 65d 232d 27/28 upstream: reported C repro on 2024/10/25 22:56
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2025/06/12 14:21 14m retest repro android13-5.10-lts OK log
2025/06/12 14:21 12m retest repro android13-5.10-lts OK log
2025/06/12 14:21 11m retest repro android13-5.10-lts OK log
2025/06/12 14:21 14m retest repro android13-5.10-lts OK log
2025/06/12 14:21 14m retest repro android13-5.10-lts OK log
2025/05/29 13:36 11m retest repro android13-5.10-lts OK log
2025/05/29 13:36 13m retest repro android13-5.10-lts OK log
2025/05/29 13:36 14m retest repro android13-5.10-lts OK log
2025/05/29 13:36 19m retest repro android13-5.10-lts OK log
2025/05/29 13:36 15m retest repro android13-5.10-lts OK log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2025/05/25 02:13 4h54m bisect fix android13-5.10-lts OK (1) job log
2025/02/08 15:28 1h03m bisect fix android13-5.10-lts OK (0) job log log
2024/10/28 17:45 2h11m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
EXT4-fs (loop0): mounted filesystem without journal. Opts: journal_ioprio=0x0000000000000005,nogrpid,block_validity,minixdf,resgid=0x0000000000000000,sysvgroups,usrjquota=,,errors=continue
==================================================================
BUG: KASAN: use-after-free in ext4_insert_dentry+0x392/0x710 fs/ext4/namei.c:2119
Write of size 250 at addr ffff88811ff24f18 by task syz-executor355/318

CPU: 0 PID: 318 Comm: syz-executor355 Not tainted 5.10.234-syzkaller-00031-gfc9aa81462ee #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:452
 kasan_check_range+0x293/0x2a0 mm/kasan/generic.c:189
 memcpy+0x44/0x70 mm/kasan/shadow.c:66
 ext4_insert_dentry+0x392/0x710 fs/ext4/namei.c:2119
 add_dirent_to_buf+0x3ac/0x780 fs/ext4/namei.c:2163
 make_indexed_dir+0xe9f/0x1500 fs/ext4/namei.c:2354
 ext4_add_entry+0xdcf/0x1280 fs/ext4/namei.c:2460
 ext4_mkdir+0x4d2/0xba0 fs/ext4/namei.c:3019
 vfs_mkdir+0x4cf/0x6c0 fs/namei.c:3790
 do_mkdirat+0x1a6/0x2c0 fs/namei.c:3812
 __do_sys_mkdirat fs/namei.c:3823 [inline]
 __se_sys_mkdirat fs/namei.c:3821 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3821
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f054cf743a9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 21 18 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffdbade618 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f054cf743a9
RDX: 0000000000000000 RSI: 00004000000005c0 RDI: 00000000ffffff9c
RBP: 0000400000000180 R08: 00007fffdbade650 R09: 00007fffdbade650
R10: 00007fffdbade650 R11: 0000000000000246 R12: 00007fffdbade63c
R13: 0000000000000009 R14: 431bde82d7b634db R15: 00007fffdbade670

The buggy address belongs to the page:
page:ffffea00047fc900 refcount:3 mapcount:0 mapping:ffff8881004497d0 index:0x3f pfn:0x11ff24
aops:def_blk_aops ino:0
flags: 0x400000000000202a(referenced|dirty|active|private)
raw: 400000000000202a dead000000000100 dead000000000122 ffff8881004497d0
raw: 000000000000003f ffff88811bfd7f18 00000003ffffffff ffff888100138000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888100138000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 318, ts 22030496098, free_ts 21953915144
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x166/0x180 mm/page_alloc.c:2462
 get_page_from_freelist+0x2d8c/0x2f30 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x435/0xaf0 mm/page_alloc.c:5348
 __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]
 __page_cache_alloc include/linux/pagemap.h:290 [inline]
 pagecache_get_page+0x669/0x950 mm/filemap.c:1848
 find_or_create_page include/linux/pagemap.h:402 [inline]
 grow_dev_page fs/buffer.c:976 [inline]
 grow_buffers fs/buffer.c:1045 [inline]
 __getblk_slow fs/buffer.c:1072 [inline]
 __getblk_gfp+0x221/0x7e0 fs/buffer.c:1370
 sb_getblk include/linux/buffer_head.h:361 [inline]
 ext4_getblk+0x259/0x660 fs/ext4/inode.c:877
 ext4_bread+0x2f/0x1b0 fs/ext4/inode.c:922
 ext4_append+0x29a/0x4d0 fs/ext4/namei.c:83
 make_indexed_dir+0x505/0x1500 fs/ext4/namei.c:2280
 ext4_add_entry+0xdcf/0x1280 fs/ext4/namei.c:2460
 ext4_mkdir+0x4d2/0xba0 fs/ext4/namei.c:3019
 vfs_mkdir+0x4cf/0x6c0 fs/namei.c:3790
 do_mkdirat+0x1a6/0x2c0 fs/namei.c:3812
 __do_sys_mkdirat fs/namei.c:3823 [inline]
 __se_sys_mkdirat fs/namei.c:3821 [inline]
 __x64_sys_mkdirat+0x7b/0x90 fs/namei.c:3821
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
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+0x2ae/0x2d0 mm/page_alloc.c:3336
 free_unref_page_list+0x122/0xb20 mm/page_alloc.c:3443
 release_pages+0xea0/0xef0 mm/swap.c:1103
 __pagevec_release+0x84/0x100 mm/swap.c:1123
 pagevec_release include/linux/pagevec.h:88 [inline]
 shmem_undo_range+0x7d1/0x1a60 mm/shmem.c:965
 shmem_truncate_range mm/shmem.c:1069 [inline]
 shmem_evict_inode+0x215/0x9d0 mm/shmem.c:1169
 evict+0x526/0x9c0 fs/inode.c:612
 iput_final fs/inode.c:1736 [inline]
 iput+0x632/0x7e0 fs/inode.c:1762
 dentry_unlink_inode+0x2ea/0x3d0 fs/dcache.c:378
 __dentry_kill+0x447/0x650 fs/dcache.c:583
 dentry_kill+0xc0/0x2a0
 dput+0x40/0x80 fs/dcache.c:883
 __fput+0x52e/0x7b0 fs/file_table.c:294
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x129/0x190 kernel/task_work.c:189
 ptrace_notify+0x29e/0x350 kernel/signal.c:2280

Memory state around the buggy address:
 ffff88811ff24f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811ff24f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811ff25000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88811ff25080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811ff25100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (25):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/03/16 19:26 android13-5.10-lts fc9aa81462ee e2826670 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/16 18:56 android13-5.10-lts fc9aa81462ee e2826670 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/25 11:43 android13-5.10-lts 3f5f2283d684 d34966d1 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/26 18:38 android13-5.10-lts 139a6bb26d9d e9a9a9f2 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/04/07 05:00 android13-5.10-lts 094fc3778d6b 1c65791e .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/18 07:53 android13-5.10-lts 094fc3778d6b ce3352cd .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/18 07:16 android13-5.10-lts 094fc3778d6b ce3352cd .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/16 23:40 android13-5.10-lts fc9aa81462ee e2826670 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/16 22:17 android13-5.10-lts fc9aa81462ee e2826670 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/03/16 21:16 android13-5.10-lts fc9aa81462ee e2826670 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/28 12:16 android13-5.10-lts 3f5f2283d684 6a8fcbc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/25 17:03 android13-5.10-lts 3f5f2283d684 d34966d1 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/25 14:51 android13-5.10-lts 3f5f2283d684 d34966d1 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/25 13:25 android13-5.10-lts 3f5f2283d684 d34966d1 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2025/02/25 12:33 android13-5.10-lts 3f5f2283d684 d34966d1 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/27 02:17 android13-5.10-lts 139a6bb26d9d e9a9a9f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/27 02:01 android13-5.10-lts 139a6bb26d9d e9a9a9f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/25 07:00 android13-5.10-lts b14940b90491 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/25 07:00 android13-5.10-lts b14940b90491 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/25 07:00 android13-5.10-lts b14940b90491 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/23 13:55 android13-5.10-lts b14940b90491 68da6d95 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/22 20:22 android13-5.10-lts b14940b90491 4b25d554 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/21 18:07 android13-5.10-lts b14940b90491 4b25d554 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/11/02 18:44 android13-5.10-lts e5e5644ea27f f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
2024/09/14 11:47 android13-5.10-lts 8d23314f588a c7e35043 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Write in ext4_insert_dentry
* Struck through repros no longer work on HEAD.