syzbot

 sign-in | mailing list | source | docs
🐞 Open [124]
🐞 Fixed [70]
🐞 Invalid [215]
≡ 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: 268d, last: 48d
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 origin:upstream missing-backport C done 10 40d 225d 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 16d 191d 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 34d 64d 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 41d 191d 3/3 fixed on 2025/06/02 10:49
upstream KASAN: use-after-free Write in ext4_insert_dentry ext4 C done 117 59d 226d 27/28 upstream: reported C repro on 2024/10/25 22:56
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
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
2025/05/10 14:56 1h26m retest repro android13-5.10-lts OK log
2025/04/21 18:43 6m retest repro android13-5.10-lts report log
2025/04/21 18:43 11m retest repro android13-5.10-lts report log
2025/04/21 18:43 7m retest repro android13-5.10-lts report log
2025/04/21 18:43 7m retest repro android13-5.10-lts report 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 error (device loop0): ext4_xattr_inode_iget:409: comm syz-executor165: error while reading EA inode 1 err=-117
EXT4-fs (loop0): 1 orphan inode deleted
EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue
==================================================================
BUG: KASAN: use-after-free in ext4_insert_dentry+0x392/0x710 fs/ext4/namei.c:2119
Write of size 250 at addr ffff88811ba44f18 by task syz-executor165/303

CPU: 1 PID: 303 Comm: syz-executor165 Not tainted 5.10.234-syzkaller-00033-g094fc3778d6b #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: 0033:0x7f04dfcae269
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:00007ffd454b2328 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f04dfcae269
RDX: 0000000000000000 RSI: 00004000000005c0 RDI: 00000000ffffff9c
RBP: 0000400000000180 R08: 00007ffd454b2360 R09: 00007ffd454b2360
R10: 00007ffd454b2360 R11: 0000000000000246 R12: 00007ffd454b234c
R13: 0000000000000004 R14: 431bde82d7b634db R15: 00007ffd454b2380

The buggy address belongs to the page:
page:ffffea00046e9100 refcount:3 mapcount:0 mapping:ffff888100449c10 index:0x3f pfn:0x11ba44
aops:def_blk_aops ino:0
flags: 0x400000000000202a(referenced|dirty|active|private)
raw: 400000000000202a dead000000000100 dead000000000122 ffff888100449c10
raw: 000000000000003f ffff88811c3d7000 00000003ffffffff ffff88810013e000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88810013e000
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 303, ts 24048375401, free_ts 23997920917
 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
 free_pages_and_swap_cache+0x8a/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+0x177/0x320 mm/mmu_gather.c:326
 unmap_region+0x31c/0x370 mm/mmap.c:2799
 __do_munmap+0x699/0x8c0 mm/mmap.c:3029
 __vm_munmap mm/mmap.c:3082 [inline]
 __do_sys_munmap mm/mmap.c:3108 [inline]
 __se_sys_munmap+0x120/0x1a0 mm/mmap.c:3104
 __x64_sys_munmap+0x5b/0x70 mm/mmap.c:3104
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88811ba44f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88811ba44f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88811ba45000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88811ba45080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811ba45100: 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
2025/03/18 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
2025/03/16 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
2025/02/28 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.