KASAN: slab-out-of-bounds Read in ext4_read_inline_dir

Status: upstream: reported C repro on 2025/07/21 09:03
Reported-by: syzbot+f2da251f196d5f1a9dac@syzkaller.appspotmail.com
First crash: 446d, last: 23d
Fix bisection: failed (error log)
  
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in ext4_read_inline_dir (2) origin:upstream 19 syz, C error 7 6d13h 648d 0/2 upstream: reported C repro on 2024/12/31 16:48
upstream KASAN: slab-out-of-bounds Read in ext4_read_inline_dir ext4 19 syz, C done error 79 364d 804d 0/29 auto-obsoleted due to no activity on 2026/01/25 02:41
android-6-1 KASAN: use-after-free Read in ext4_read_inline_dir 19 1 803d 803d 0/2 auto-obsoleted due to no activity on 2024/10/28 03:11
android-5-15 KASAN: use-after-free Read in ext4_read_inline_dir origin:upstream 19 syz, C error 7 36d 641d 0/2 upstream: reported C repro on 2025/01/07 14:17
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/10/10 22:32 23m retest repro android13-5.10-lts no crash job log log
2026/08/28 19:45 1h39m retest repro android13-5.10-lts report job log log
2026/08/28 19:45 13m retest repro android13-5.10-lts report job log log
2026/08/28 19:45 19m retest repro android13-5.10-lts no crash job log log
2026/06/28 07:55 15m retest repro android13-5.10-lts log
2026/05/18 20:42 21m retest repro android13-5.10-lts log
2026/04/08 05:21 5m retest repro android13-5.10-lts report log
2026/03/03 23:32 14m retest repro android13-5.10-lts report log
2026/01/28 03:07 14m retest repro android13-5.10-lts report log
2025/12/23 22:18 12m retest repro android13-5.10-lts report log
▶ ▼ Fix bisection attempts (2)
Created Duration User Patch Repo Result
2025/11/18 21:04 0m bisect fix android13-5.10-lts error
2025/09/13 16:53 2h00m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
EXT4-fs (loop2): mounted filesystem without journal. Opts: resgid=0x000000000000ee00,bsddf,grpquota,nojournal_checksum,debug_want_extra_isize=0x0000000000000080,delalloc,nogrpid,noauto_da_alloc,stripe=0x0000000000000002,,errors=continue
==================================================================
BUG: KASAN: use-after-free in ext4_read_inline_data fs/ext4/inline.c:209 [inline]
BUG: KASAN: use-after-free in ext4_read_inline_dir+0x414/0xd00 fs/ext4/inline.c:1541
Read of size 68 at addr ffff888110fac41e by task syz.2.17/367

CPU: 0 PID: 367 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
 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_read_inline_dir+0x414/0xd00 fs/ext4/inline.c:1541
 ext4_readdir+0x3a0/0x3a80 fs/ext4/dir.c:161
 iterate_dir+0x25c/0x560 fs/readdir.c:-1
 __do_sys_getdents fs/readdir.c:286 [inline]
 __se_sys_getdents+0xf2/0x250 fs/readdir.c:271
 __x64_sys_getdents+0x7b/0x90 fs/readdir.c:271
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f85142e2e99
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:00007ffcd4e7aac8 EFLAGS: 00000246 ORIG_RAX: 000000000000004e
RAX: ffffffffffffffda RBX: 00007f851456afa0 RCX: 00007f85142e2e99
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f8514378eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f851456afac R14: 00007f851456afa0 R15: 00007f851456afa0

Allocated by task 0:
(stack is not available)

Freed by task 7:
 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]
 kfree+0xc0/0x270 mm/slub.c:4196
 skb_free_head net/core/skbuff.c:606 [inline]
 skb_release_data+0x53b/0x690 net/core/skbuff.c:626
 skb_release_all net/core/skbuff.c:680 [inline]
 __kfree_skb net/core/skbuff.c:694 [inline]
 consume_skb+0xab/0x1f0 net/core/skbuff.c:851
 netlink_broadcast_filtered+0x11ce/0x12c0 net/netlink/af_netlink.c:1535
 netlink_broadcast net/netlink/af_netlink.c:1557 [inline]
 nlmsg_multicast include/net/netlink.h:1033 [inline]
 nlmsg_notify+0xe9/0x1a0 net/netlink/af_netlink.c:2551
 rtnl_notify net/core/rtnetlink.c:740 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:3872 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:3887 [inline]
 rtmsg_ifinfo+0xea/0x130 net/core/rtnetlink.c:3893
 dev_close_many+0x26e/0x4d0 net/core/dev.c:1652
 unregister_netdevice_many+0x477/0x19f0 net/core/dev.c:10755
 default_device_exit_batch+0x35e/0x3c0 net/core/dev.c:11298
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x5fe/0xb80 net/core/net_namespace.c:609
 process_one_work+0x6fd/0xbc0 kernel/workqueue.c:2301
 worker_thread+0xa8e/0x13c0 kernel/workqueue.c:2447
 kthread+0x324/0x3b0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff888110fac000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 1054 bytes inside of
 2048-byte region [ffff888110fac000, ffff888110fac800)
The buggy address belongs to the page:
page:ffffea000443ea00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x110fa8
head:ffffea000443ea00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 dead000000000100 dead000000000122 ffff888100042d80
raw: 0000000000000000 0000000000080008 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 0x1d2a20(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 7, ts 31613633437, free_ts 31606726256
 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]
 __kmalloc_track_caller+0x1e4/0x310 mm/slub.c:4541
 __kmalloc_reserve net/core/skbuff.c:144 [inline]
 __alloc_skb+0xdc/0x520 net/core/skbuff.c:212
 alloc_skb include/linux/skbuff.h:1126 [inline]
 alloc_skb_with_frags+0xa3/0x560 net/core/skbuff.c:6006
 sock_alloc_send_pskb+0x87f/0x9a0 net/core/sock.c:2393
 sock_alloc_send_skb+0x32/0x40 net/core/sock.c:2410
 mld_newpack+0x1b3/0x9e0 net/ipv6/mcast.c:1604
 add_grhead net/ipv6/mcast.c:1707 [inline]
 add_grec+0xedf/0x1330 net/ipv6/mcast.c:1838
 mld_send_cr net/ipv6/mcast.c:1964 [inline]
 mld_ifc_timer_expire+0x797/0xc60 net/ipv6/mcast.c:2471
 call_timer_fn+0x38/0x290 kernel/time/timer.c:1450
 expire_timers kernel/time/timer.c:1495 [inline]
 __run_timers+0x637/0x9a0 kernel/time/timer.c:1789
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]
 syslog_print+0x127/0x720 kernel/printk/printk.c:1487
 do_syslog+0x94c/0x9a0 kernel/printk/printk.c:1644
 __do_sys_syslog kernel/printk/printk.c:1736 [inline]
 __se_sys_syslog kernel/printk/printk.c:1734 [inline]
 __x64_sys_syslog+0x7c/0x90 kernel/printk/printk.c:1734

Memory state around the buggy address:
 ffff888110fac300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888110fac380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888110fac400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff888110fac480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888110fac500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (20):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/18 12:24 android13-5.10-lts 50b3a256e550 72524a66 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/07/18 12:01 android13-5.10-lts 50b3a256e550 72524a66 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/07/09 03:28 android13-5.10-lts 50b3a256e550 b9f1ceaa .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_read_inline_dir
2025/07/21 08:53 android13-5.10-lts 6de38b5f6c2b 7117feec .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_read_inline_dir
2025/07/21 08:10 android13-5.10-lts 6de38b5f6c2b 7117feec .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro (corrupt fs)] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_read_inline_dir
2026/09/18 00:16 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:15 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:15 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:15 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:14 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:13 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:13 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:13 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:11 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:11 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:10 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: out-of-bounds Read in ext4_read_inline_dir
2026/09/18 00:09 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:09 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:07 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
2026/09/18 00:07 android13-5.10-lts 452567d1985b 8d7d05f1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in ext4_read_inline_dir
* Struck through repros no longer work on HEAD.