syzbot

 sign-in | mailing list | source | docs
🐞 Open [139]
🐞 Fixed [69]
🐞 Invalid [295]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

KASAN: use-after-free Read in ext4_convert_inline_data_nolock (2)

Status: upstream: reported C repro on 2026/06/21 08:24
Reported-by: syzbot+90de828ca945fb262dc0@syzkaller.appspotmail.com
First crash: 3d04h, last: 17h28m
▶ ▼ Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 KASAN: use-after-free Read in ext4_convert_inline_data_nolock origin:upstream 19 C error 1 29d 1128d 0/3 upstream: reported C repro on 2023/05/21 13:36
upstream KASAN: slab-use-after-free Read in ext4_convert_inline_data_nolock ext4 19 C error done 7 906d 1183d 25/29 fixed on 2024/02/03 12:44
android-5-10 KASAN: use-after-free Read in ext4_convert_inline_data_nolock 19 syz error 1 650d 783d 0/2 auto-obsoleted due to no activity on 2024/12/28 07:38
android-5-15 KASAN: use-after-free Read in ext4_convert_inline_data_nolock (2) 19 C 4 18h40m 19h40m 0/2 upstream: reported C repro on 2026/06/22 03:50
android-6-1 KASAN: use-after-free Read in ext4_convert_inline_data_nolock origin:upstream missing-backport 19 C done 2 587d 783d 0/2 auto-obsoleted due to no activity on 2025/02/20 23:05
android-5-15 KASAN: use-after-free Read in ext4_convert_inline_data_nolock missing-backport origin:upstream 19 C error 1 599d 754d 0/2 auto-obsoleted due to no activity on 2025/02/08 19:49
linux-6.1 KASAN: use-after-free Read in ext4_convert_inline_data_nolock origin:upstream 19 C error 2 489d 1164d 0/3 upstream: reported C repro on 2023/04/15 09:27
android-54 KASAN: use-after-free Read in ext4_convert_inline_data_nolock 19 C 1 617d 783d 0/2 auto-obsoleted due to no activity on 2025/03/03 02:23

Sample crash report:
EXT4-fs (loop0): mounted filesystem without journal. Opts: max_batch_time=0x0000000000000004,max_batch_time=0x0000000000000002,resuid=0x0000000000000000,block_validity,errors=remount-ro,nombcache,
==================================================================
BUG: KASAN: use-after-free in ext4_read_inline_data fs/ext4/inline.c:209 [inline]
BUG: KASAN: use-after-free in ext4_convert_inline_data_nolock+0x313/0xcc0 fs/ext4/inline.c:1242
Read of size 68 at addr ffff888112f85c80 by task syz.0.17/391

CPU: 1 PID: 391 Comm: syz.0.17 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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x249/0x2a0 mm/kasan/generic.c:189
 memcpy+0x2d/0x70 mm/kasan/shadow.c:65
 ext4_read_inline_data fs/ext4/inline.c:209 [inline]
 ext4_convert_inline_data_nolock+0x313/0xcc0 fs/ext4/inline.c:1242
 ext4_try_add_inline_entry+0x73d/0xa70 fs/ext4/inline.c:1367
 ext4_add_entry+0x674/0xf90 fs/ext4/namei.c:2414
 ext4_mkdir+0x509/0xc60 fs/ext4/namei.c:3019
 vfs_mkdir+0x42c/0x600 fs/namei.c:3798
 do_mkdirat+0x14c/0x340 fs/namei.c:3820
 __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: 0033:0x7f494a3fccc7
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:00007fff5539e788 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fff5539e810 RCX: 00007f494a3fccc7
RDX: 00000000000001ff RSI: 0000200000000080 RDI: 00000000ffffff9c
RBP: 0000200000000140 R08: 0000200000000080 R09: 0000000000000000
R10: 0000200000000140 R11: 0000000000000246 R12: 0000200000000080
R13: 00007fff5539e7d0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 95:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track mm/kasan/common.c:45 [inline]
 set_alloc_info mm/kasan/common.c:430 [inline]
 __kasan_slab_alloc+0xb7/0xe0 mm/kasan/common.c:463
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x15a/0x2d0 mm/slub.c:2965
 getname_flags+0xba/0x510 fs/namei.c:141
 getname+0x19/0x20 fs/namei.c:212
 do_sys_openat2+0xde/0x750 fs/open.c:1213
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 95:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 mm/kasan/common.c:362
 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:370
 kasan_slab_free include/linux/kasan.h:220 [inline]
 slab_free_hook mm/slub.c:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kmem_cache_free+0x100/0x2d0 mm/slub.c:3224
 putname+0xfe/0x150 fs/namei.c:262
 do_sys_openat2+0x68e/0x750 fs/open.c:1228
 do_sys_open fs/open.c:1235 [inline]
 __do_sys_openat fs/open.c:1251 [inline]
 __se_sys_openat fs/open.c:1246 [inline]
 __x64_sys_openat+0x136/0x160 fs/open.c:1246
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

The buggy address belongs to the object at ffff888112f85500
 which belongs to the cache names_cache of size 4096
The buggy address is located 1920 bytes inside of
 4096-byte region [ffff888112f85500, ffff888112f86500)
The buggy address belongs to the page:
page:ffffea00044be000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x112f80
head:ffffea00044be000 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff88810018a180
raw: 0000000000000000 0000000000070007 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 310, ts 24462497435, free_ts 24397330840
 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_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc+0x1a4/0x2d0 mm/slub.c:2965
 getname_flags+0xba/0x510 fs/namei.c:141
 getname fs/namei.c:212 [inline]
 user_path_create fs/namei.c:3673 [inline]
 do_symlinkat+0x7a/0x3d0 fs/namei.c:4127
 __do_sys_symlink fs/namei.c:4153 [inline]
 __se_sys_symlink fs/namei.c:4151 [inline]
 __x64_sys_symlink+0x60/0x70 fs/namei.c:4151
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 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_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5445 [inline]
 __free_pages+0xd8/0x390 mm/page_alloc.c:5454
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x150/0x180 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x10e/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc_trace+0x155/0x2e0 mm/slub.c:2977
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 alloc_fs_context+0x65/0x630 fs/fs_context.c:234
 fs_context_for_mount+0x22/0x30 fs/fs_context.c:281
 do_new_mount+0x122/0xa30 fs/namespace.c:2985

Memory state around the buggy address:
 ffff888112f85b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888112f85c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888112f85c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888112f85d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888112f85d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
EXT4-fs error (device loop0): ext4_check_all_de:659: inode #12: block 7: comm syz.0.17: bad entry in directory: directory entry overrun - offset=0, inode=901261600, rec_len=7976, size=124 fake=0
EXT4-fs (loop0): Remounting filesystem read-only

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/22 06:01 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_convert_inline_data_nolock
2026/06/22 05:29 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_convert_inline_data_nolock
2026/06/22 04:54 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: slab-out-of-bounds Read in ext4_convert_inline_data_nolock
2026/06/21 11:01 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: slab-out-of-bounds Read in ext4_convert_inline_data_nolock
2026/06/21 08:13 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: slab-out-of-bounds Read in ext4_convert_inline_data_nolock
2026/06/21 07:49 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: slab-out-of-bounds Read in ext4_convert_inline_data_nolock
2026/06/21 08:26 android13-5.10-lts 6321e6c974f1 43bfcdb0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_convert_inline_data_nolock
2026/06/19 19:27 android13-5.10-lts 6321e6c974f1 570c59ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_convert_inline_data_nolock
* Struck through repros no longer work on HEAD.