KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree

Status: upstream: reported C repro on 2024/07/21 20:19
Reported-by: syzbot+ed1375847e58c67f38b8@syzkaller.appspotmail.com
First crash: 747d, last: 8d01h
▶ ▼ Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in ext4_htree_fill_tree missing-backport origin:upstream 19 syz, C error 9 104d 593d 0/2 upstream: reported C repro on 2024/12/22 19:07
android-5-15 KASAN: use-after-free Read in ext4_htree_fill_tree origin:upstream missing-backport 19 syz, C error 9 115d 588d 0/2 upstream: reported C repro on 2024/12/27 19:48
linux-6.1 KASAN: use-after-free Read in ext4_htree_fill_tree 19 1 694d 694d 0/3 auto-obsoleted due to no activity on 2024/12/22 07:44
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/07/31 07:22 1h33m retest repro android13-5.10-lts report log
2026/07/31 07:22 25m retest repro android13-5.10-lts report log
2026/07/31 07:22 1h04m retest repro android13-5.10-lts report log
2026/07/31 07:22 25m retest repro android13-5.10-lts report log
2026/07/31 07:22 23m retest repro android13-5.10-lts report log
2026/07/25 15:33 12m retest repro android13-5.10-lts log
2026/07/25 15:33 13m retest repro android13-5.10-lts log
2026/07/25 15:33 11m retest repro android13-5.10-lts log
2026/07/25 15:33 20m retest repro android13-5.10-lts log
2026/07/25 15:33 26m retest repro android13-5.10-lts log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2026/07/08 20:04 1h13m bisect fix android13-5.10-lts OK (0) job log log
2026/06/07 23:15 1h20m bisect fix android13-5.10-lts OK (0) job log log
2024/09/09 00:15 40m bisect fix android13-5.10-lts OK (0) job log log

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in ext4_htree_fill_tree+0x1316/0x13e0 fs/ext4/namei.c:1221
Read of size 1 at addr ffff88810f7b9535 by task syz-executor235/293

CPU: 0 PID: 293 Comm: syz-executor235 Not tainted 5.10.226-syzkaller-00326-gab7c0abef9cf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:306
 ext4_htree_fill_tree+0x1316/0x13e0 fs/ext4/namei.c:1221
 ext4_dx_readdir fs/ext4/dir.c:598 [inline]
 ext4_readdir+0x2dde/0x37c0 fs/ext4/dir.c:142
 iterate_dir+0x265/0x580
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0x1c1/0x460 fs/readdir.c:354
 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354
 do_syscall_64+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fdc4c571923
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 02 1d fb ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 b8 ff ff ff f7 d8
RSP: 002b:00007ffeffa6f988 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00005555895a3730 RCX: 00007fdc4c571923
RDX: 0000000000008000 RSI: 00005555895a3730 RDI: 0000000000000004
RBP: 00005555895a3704 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: ffffffffffffffb8
R13: 0000000000000010 R14: 00005555895a3700 R15: 0000000000000001

Allocated by task 96:
 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_kmalloc+0xdb/0x110 mm/kasan/common.c:509
 __kasan_kmalloc+0x9/0x10 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 kmem_cache_alloc_trace+0x18a/0x2e0 mm/slub.c:2974
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 kobject_uevent_env+0x269/0x700 lib/kobject_uevent.c:539
 kobject_synth_uevent+0x4eb/0xae0 lib/kobject_uevent.c:208
 store_uevent+0x16/0x30 kernel/module.c:1233
 module_attr_store+0x5c/0x80 kernel/params.c:921
 sysfs_kf_write+0x123/0x140 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x2c4/0x410 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2023 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0xb4c/0xe70 fs/read_write.c:605
 ksys_write+0x199/0x2c0 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+0x34/0x70
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 48:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x121/0x160 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:1595 [inline]
 slab_free_freelist_hook+0xc0/0x190 mm/slub.c:1621
 slab_free mm/slub.c:3203 [inline]
 kfree+0xc3/0x270 mm/slub.c:4191
 skb_free_head net/core/skbuff.c:606 [inline]
 pskb_expand_head+0x390/0x1180 net/core/skbuff.c:1686
 netlink_trim+0x19b/0x230 net/netlink/af_netlink.c:1304
 netlink_broadcast_filtered+0x66/0x1270 net/netlink/af_netlink.c:1509
 netlink_broadcast net/netlink/af_netlink.c:1554 [inline]
 nlmsg_multicast include/net/netlink.h:1033 [inline]
 nlmsg_notify+0x101/0x1c0 net/netlink/af_netlink.c:2542
 rtnl_notify net/core/rtnetlink.c:737 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:3865 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:3880 [inline]
 rtmsg_ifinfo+0xe7/0x120 net/core/rtnetlink.c:3886
 netdev_state_change+0x1be/0x250 net/core/dev.c:1486
 linkwatch_do_dev+0x100/0x140 net/core/link_watch.c:167
 __linkwatch_run_queue+0x4ca/0x7f0 net/core/link_watch.c:213
 linkwatch_event+0x4c/0x60 net/core/link_watch.c:252
 process_one_work+0x6dc/0xbd0 kernel/workqueue.c:2301
 worker_thread+0xaea/0x1510 kernel/workqueue.c:2447
 kthread+0x34b/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff88810f7b8000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1333 bytes to the right of
 4096-byte region [ffff88810f7b8000, ffff88810f7b9000)
The buggy address belongs to the page:
page:ffffea00043dee00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10f7b8
head:ffffea00043dee00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00043de000 0000000200000002 ffff888100042c00
raw: 0000000000000000 0000000000040004 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 96, ts 3915401879, 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+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
 allocate_slab mm/slub.c:1808 [inline]
 new_slab+0x80/0x400 mm/slub.c:1869
 new_slab_objects mm/slub.c:2627 [inline]
 ___slab_alloc+0x302/0x4b0 mm/slub.c:2791
 __slab_alloc+0x63/0xa0 mm/slub.c:2831
 slab_alloc_node mm/slub.c:2913 [inline]
 slab_alloc mm/slub.c:2955 [inline]
 kmem_cache_alloc_trace+0x1bd/0x2e0 mm/slub.c:2972
 kmalloc include/linux/slab.h:552 [inline]
 kzalloc include/linux/slab.h:664 [inline]
 kobject_uevent_env+0x269/0x700 lib/kobject_uevent.c:539
 kobject_synth_uevent+0x4eb/0xae0 lib/kobject_uevent.c:208
 store_uevent+0x16/0x30 kernel/module.c:1233
 module_attr_store+0x5c/0x80 kernel/params.c:921
 sysfs_kf_write+0x123/0x140 fs/sysfs/file.c:139
 kernfs_fop_write_iter+0x2c4/0x410 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2023 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0xb4c/0xe70 fs/read_write.c:605
 ksys_write+0x199/0x2c0 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
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810f7b9400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810f7b9480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810f7b9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff88810f7b9580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810f7b9600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (14):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/03 12:18 android13-5.10-lts ab7c0abef9cf 578925bc .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2024/09/27 11:44 android13-5.10-lts 8d23314f588a 9314348a .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2024/07/21 22:17 android13-5.10-lts 1240968f7644 b88348e9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2024/07/21 20:54 android13-5.10-lts 1240968f7644 b88348e9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2024/07/21 20:10 android13-5.10-lts 1240968f7644 b88348e9 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2025/01/14 20:35 android13-5.10-lts fbe98d68b6b3 f310a27d .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/11/14 13:50 android13-5.10-lts 6a01908517df a8c99394 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/10/31 05:41 android13-5.10-lts e5e5644ea27f 96eb609f .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/09/28 01:34 android13-5.10-lts 8d23314f588a 440b26ec .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/07/21 21:36 android13-5.10-lts 1240968f7644 b88348e9 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/09/27 13:19 android13-5.10-lts 8d23314f588a 9314348a .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2024/09/27 10:29 android13-5.10-lts 8d23314f588a 9314348a .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
2025/02/06 15:05 android13-5.10-lts fbe98d68b6b3 577d049b .config console log report syz / log [disk image] [vmlinux] [kernel image] [mounted in repro #1] [mounted in repro #2] ci2-android-5-10 KASAN: use-after-free Read in ext4_htree_fill_tree
2024/07/21 19:23 android13-5.10-lts 1240968f7644 b88348e9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: slab-out-of-bounds Read in ext4_htree_fill_tree
* Struck through repros no longer work on HEAD.