syzbot

 sign-in | mailing list | source | docs
🐞 Open [144]
🐞 Fixed [69]
🐞 Invalid [302]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
💬 Send us feedback

KASAN: use-after-free Read in ext4_xattr_ibody_get

Status: upstream: reported C repro on 2026/02/24 05:00
Reported-by: syzbot+8033bf14e2a4aa787ba6@syzkaller.appspotmail.com
First crash: 144d, last: 1d10h
▶ ▼ Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 KASAN: use-after-free Read in ext4_xattr_ibody_get origin:upstream 19 C 8 1d10h 46d 0/2 upstream: reported C repro on 2026/06/02 13:41
▶ ▼ Last patch testing requests (5)
Created Duration User Patch Repo Result
2026/06/10 13:52 13m retest repro android13-5.10-lts log
2026/06/10 13:52 13m retest repro android13-5.10-lts log
2026/06/10 13:52 16m retest repro android13-5.10-lts log
2026/06/10 13:52 12m retest repro android13-5.10-lts log
2026/03/10 05:57 10m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/06/20 17:02 1h03m bisect fix android13-5.10-lts OK (0) job log log
2026/05/09 09:52 2h12m bisect fix android13-5.10-lts OK (0) job log log
2026/04/09 06:15 1h10m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
EXT4-fs (loop2): mounted filesystem without journal. Opts: block_validity,errors=remount-ro,sysvgroups,norecovery,debug_want_extra_isize=0x0000000000000080,grpjquota=,nogrpid,noauto_da_alloc,norecovery,
==================================================================
BUG: KASAN: use-after-free in xattr_find_entry fs/ext4/xattr.c:294 [inline]
BUG: KASAN: use-after-free in ext4_xattr_ibody_get+0x606/0x670 fs/ext4/xattr.c:601
Read of size 4 at addr ffff888111bfc004 by task syz.2.18/400

CPU: 0 PID: 400 Comm: syz.2.18 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/25/2026
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_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 xattr_find_entry fs/ext4/xattr.c:294 [inline]
 ext4_xattr_ibody_get+0x606/0x670 fs/ext4/xattr.c:601
 ext4_xattr_get+0x116/0x830 fs/ext4/xattr.c:655
 ext4_get_acl+0x6c/0x6b0 fs/ext4/acl.c:162
 get_acl+0x15f/0x270 fs/posix_acl.c:141
 posix_acl_chmod+0xe1/0x240 fs/posix_acl.c:565
 ext4_setattr+0xb65/0x1980 fs/ext4/inode.c:5741
 notify_change+0xab5/0xe40 fs/attr.c:410
 chmod_common+0x1e4/0x390 fs/open.c:584
 do_fchmodat+0xd4/0x1a0 fs/open.c:622
 __do_sys_fchmodat fs/open.c:635 [inline]
 __se_sys_fchmodat fs/open.c:632 [inline]
 __x64_sys_fchmodat+0x7b/0x90 fs/open.c:632
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f13e1b92e99
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffdc4be848 EFLAGS: 00000246 ORIG_RAX: 000000000000010c
RAX: ffffffffffffffda RBX: 00007f13e1e1afa0 RCX: 00007f13e1b92e99
RDX: 00000000ffffff50 RSI: 0000200000000300 RDI: ffffffffffffff9c
RBP: 00007f13e1c28eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f13e1e1afac R14: 00007f13e1e1afa0 R15: 00007f13e1e1afa0

Allocated by task 107:
 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
 kmem_cache_alloc_node include/linux/slab.h:426 [inline]
 __alloc_skb+0x9e/0x520 net/core/skbuff.c:200
 alloc_skb include/linux/skbuff.h:1126 [inline]
 alloc_uevent_skb+0x85/0x240 lib/kobject_uevent.c:290
 uevent_net_broadcast_untagged lib/kobject_uevent.c:326 [inline]
 kobject_uevent_net_broadcast+0x335/0x5a0 lib/kobject_uevent.c:409
 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x452/0x940 lib/kobject_uevent.c:208
 uevent_store+0x25/0x60 drivers/base/core.c:2320
 dev_attr_store+0x5e/0x80 drivers/base/core.c:2018
 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2066 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 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 ffff888111bfc000
 which belongs to the cache skbuff_head_cache of size 248
The buggy address is located 4 bytes inside of
 248-byte region [ffff888111bfc000, ffff888111bfc0f8)
The buggy address belongs to the page:
page:ffffea000446ff00 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888111bfca00 pfn:0x111bfc
flags: 0x4000000000000200(slab)
raw: 4000000000000200 0000000000000000 0000000100000001 ffff888107d93200
raw: ffff888111bfca00 00000000800c0000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 107, ts 4474818371, free_ts 0
 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
 skb_clone+0x1cd/0x370 net/core/skbuff.c:1467
 do_one_broadcast net/netlink/af_netlink.c:1453 [inline]
 netlink_broadcast_filtered+0x66e/0x12c0 net/netlink/af_netlink.c:1533
 netlink_broadcast+0x3a/0x50 net/netlink/af_netlink.c:1557
 uevent_net_broadcast_untagged lib/kobject_uevent.c:331 [inline]
 kobject_uevent_net_broadcast+0x3bd/0x5a0 lib/kobject_uevent.c:409
 kobject_uevent_env+0x52b/0x700 lib/kobject_uevent.c:608
 kobject_synth_uevent+0x452/0x940 lib/kobject_uevent.c:208
 uevent_store+0x25/0x60 drivers/base/core.c:2320
 dev_attr_store+0x5e/0x80 drivers/base/core.c:2018
 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:139
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888111bfbf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888111bfbf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888111bfc000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888111bfc080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc
 ffff888111bfc100: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
==================================================================
EXT4-fs error (device loop2): xattr_find_entry:297: inode #12: comm syz.2.18: corrupted xattr entries
EXT4-fs (loop2): Remounting filesystem read-only

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/17 07:43 android13-5.10-lts 50b3a256e550 7f27c57a .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_xattr_ibody_get
2026/07/17 05:32 android13-5.10-lts 50b3a256e550 7f27c57a .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro #1 (clean fs)] [mounted in repro #2 (clean fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_xattr_ibody_get
2026/05/20 04:25 android13-5.10-lts f5a34916f66d 0909d65f .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_xattr_ibody_get
2026/05/20 03:54 android13-5.10-lts f5a34916f66d 0909d65f .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_xattr_ibody_get
2026/05/20 02:54 android13-5.10-lts f5a34916f66d 0909d65f .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_xattr_ibody_get
2026/05/20 02:24 android13-5.10-lts f5a34916f66d 0909d65f .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_xattr_ibody_get
2026/02/24 04:54 android13-5.10-lts e8b14e1cefe8 41d2fa6a .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 Read in ext4_xattr_ibody_get
2026/02/24 04:18 android13-5.10-lts e8b14e1cefe8 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_xattr_ibody_get
2026/02/24 04:18 android13-5.10-lts e8b14e1cefe8 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_xattr_ibody_get
2026/02/24 04:17 android13-5.10-lts e8b14e1cefe8 41d2fa6a .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_xattr_ibody_get
* Struck through repros no longer work on HEAD.