syzbot


KASAN: out-of-bounds Read in ext4_xattr_set_entry

Status: upstream: reported on 2025/06/17 02:45
Reported-by: syzbot+9e300b604d671b1676b3@syzkaller.appspotmail.com
First crash: 1d05h, last: 1d05h
Similar bugs (17)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.19 KASAN: use-after-free Read in ext4_xattr_set_entry (2) C done 7 1374d 1832d 1/1 fixed on 2021/10/13 07:23
android-5-15 KASAN: out-of-bounds Read in ext4_xattr_set_entry 1 730d 730d 0/2 auto-obsoleted due to no activity on 2023/09/17 07:02
upstream KASAN: out-of-bounds Read in ext4_xattr_set_entry ext4 C error 2038 25m 269d 0/28 upstream: reported C repro on 2024/09/22 00:16
android-54 KASAN: out-of-bounds Read in ext4_xattr_set_entry ext4 C 14 783d 1549d 0/2 auto-obsoleted due to no activity on 2023/08/23 09:06
linux-5.15 KASAN: out-of-bounds Read in ext4_xattr_set_entry origin:upstream C 21 2d17h 94d 0/3 upstream: reported C repro on 2025/03/15 11:50
linux-6.1 KASAN: out-of-bounds Read in ext4_xattr_set_entry missing-backport origin:lts-only C inconclusive 385 1d01h 760d 0/3 upstream: reported C repro on 2023/05/19 08:42
android-5-10 KASAN: out-of-bounds Read in ext4_xattr_set_entry C inconclusive 12 3d17h 637d 0/2 upstream: reported C repro on 2023/09/20 02:40
linux-4.14 KASAN: out-of-bounds Read in ext4_xattr_set_entry C error 2 1013d 1527d 0/1 upstream: reported C repro on 2021/04/12 14:20
android-6-1 KASAN: out-of-bounds Read in ext4_xattr_set_entry origin:lts C 215 5d10h 400d 0/2 upstream: reported C repro on 2024/05/13 18:18
android-5-15 general protection fault in ext4_xattr_set_entry C error 1 838d 918d 2/2 fixed on 2023/03/28 12:29
android-5-10 general protection fault in ext4_xattr_set_entry (4) C error 62 741d 770d 2/2 fixed on 2023/06/07 17:22
android-5-10 general protection fault in ext4_xattr_set_entry (2) ext4 C error 423 776d 976d 2/2 fixed on 2023/05/03 13:06
upstream KASAN: use-after-free Read in ext4_xattr_set_entry (5) ext4 2 1058d 1116d 0/28 auto-obsoleted due to no activity on 2022/11/22 17:19
android-5-10 general protection fault in ext4_xattr_set_entry (3) C error 9 772d 775d 2/2 fixed on 2023/05/08 19:06
upstream KASAN: use-after-free Read in ext4_xattr_set_entry (4) ext4 C error done 21 1212d 1599d 20/28 fixed on 2022/03/28 10:17
android-5-10 general protection fault in ext4_xattr_set_entry C error 2 999d 1013d 0/2 closed as invalid on 2022/09/26 18:30
android-5-10 general protection fault in ext4_xattr_set_entry (5) C done 11 738d 740d 2/2 fixed on 2023/06/13 02:27

Sample crash report:
EXT4-fs: Ignoring removed nobh option
EXT4-fs: Ignoring removed bh option
EXT4-fs (loop7): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: out-of-bounds in ext4_xattr_set_entry+0x94b/0x1e90 fs/ext4/xattr.c:1790
Read of size 18446744073709551604 at addr ffff888020ec6030 by task syz.7.4895/25646

CPU: 0 PID: 25646 Comm: syz.7.4895 Not tainted 6.6.93-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x230 mm/kasan/report.c:475
 kasan_report+0x151/0x180 mm/kasan/report.c:588
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
 __asan_memmove+0x29/0x70 mm/kasan/shadow.c:94
 ext4_xattr_set_entry+0x94b/0x1e90 fs/ext4/xattr.c:1790
 ext4_xattr_block_set+0xae3/0x32a0 fs/ext4/xattr.c:2037
 ext4_xattr_set_handle+0x10a1/0x1290 fs/ext4/xattr.c:2462
 ext4_xattr_set+0x22d/0x320 fs/ext4/xattr.c:2564
 __vfs_setxattr+0x431/0x470 fs/xattr.c:201
 __vfs_setxattr_noperm+0x12d/0x5e0 fs/xattr.c:235
 vfs_setxattr+0x16c/0x2f0 fs/xattr.c:322
 do_setxattr fs/xattr.c:630 [inline]
 path_setxattr+0x362/0x550 fs/xattr.c:659
 __do_sys_lsetxattr fs/xattr.c:684 [inline]
 __se_sys_lsetxattr fs/xattr.c:680 [inline]
 __x64_sys_lsetxattr+0xb8/0xd0 fs/xattr.c:680
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fba3d98e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fba3e783038 EFLAGS: 00000246 ORIG_RAX: 00000000000000bd
RAX: ffffffffffffffda RBX: 00007fba3dbb5fa0 RCX: 00007fba3d98e929
RDX: 00002000000001c0 RSI: 0000200000000180 RDI: 00002000000001c0
RBP: 00007fba3da10b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000361 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fba3dbb5fa0 R15: 00007ffeff95d288
 </TASK>

Allocated by task 25646:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:198 [inline]
 __do_kmalloc_node mm/slab_common.c:1007 [inline]
 __kmalloc_node_track_caller+0xb2/0x230 mm/slab_common.c:1027
 kmemdup+0x2b/0x70 mm/util.c:131
 _Z7kmemdupPKvU25pass_dynamic_object_size0mj include/linux/fortify-string.h:779 [inline]
 ext4_xattr_block_set+0x9e5/0x32a0 fs/ext4/xattr.c:1985
 ext4_xattr_set_handle+0x10a1/0x1290 fs/ext4/xattr.c:2462
 ext4_xattr_set+0x22d/0x320 fs/ext4/xattr.c:2564
 __vfs_setxattr+0x431/0x470 fs/xattr.c:201
 __vfs_setxattr_noperm+0x12d/0x5e0 fs/xattr.c:235
 vfs_setxattr+0x16c/0x2f0 fs/xattr.c:322
 do_setxattr fs/xattr.c:630 [inline]
 path_setxattr+0x362/0x550 fs/xattr.c:659
 __do_sys_lsetxattr fs/xattr.c:684 [inline]
 __se_sys_lsetxattr fs/xattr.c:680 [inline]
 __x64_sys_lsetxattr+0xb8/0xd0 fs/xattr.c:680
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:45
 __kasan_record_aux_stack+0xaf/0xc0 mm/kasan/generic.c:492
 kvfree_call_rcu+0xee/0x780 kernel/rcu/tree.c:3444
 neigh_periodic_work+0x3f7/0xd70 net/core/neighbour.c:1005
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff888020ec6000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 48 bytes inside of
 1024-byte region [ffff888020ec6000, ffff888020ec6400)

The buggy address belongs to the physical page:
page:ffffea000083b000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20ec0
head:ffffea000083b000 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017841dc0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080100010 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 0x1f2820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_MEMALLOC|__GFP_HARDWALL), pid 10513, tgid 10513 (kworker/u4:23), ts 1270820048601, free_ts 1270778919296
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 alloc_slab_page+0x5d/0x170 mm/slub.c:1876
 allocate_slab mm/slub.c:2023 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2076
 ___slab_alloc+0xc6d/0x12f0 mm/slub.c:3230
 __slab_alloc mm/slub.c:3329 [inline]
 __slab_alloc_node mm/slub.c:3382 [inline]
 slab_alloc_node mm/slub.c:3475 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3524
 __do_kmalloc_node mm/slab_common.c:1006 [inline]
 __kmalloc_node_track_caller+0xa2/0x230 mm/slab_common.c:1027
 kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
 __alloc_skb+0x138/0x2c0 net/core/skbuff.c:650
 __netdev_alloc_skb+0x10c/0x500 net/core/skbuff.c:714
 __netdev_alloc_skb_ip_align include/linux/skbuff.h:3269 [inline]
 netdev_alloc_skb_ip_align include/linux/skbuff.h:3279 [inline]
 batadv_iv_ogm_aggregate_new net/batman-adv/bat_iv_ogm.c:557 [inline]
 batadv_iv_ogm_queue_add+0x73e/0xcf0 net/batman-adv/bat_iv_ogm.c:669
 batadv_iv_ogm_schedule_buff net/batman-adv/bat_iv_ogm.c:848 [inline]
 batadv_iv_ogm_schedule+0xab3/0xe90 net/batman-adv/bat_iv_ogm.c:867
 batadv_iv_send_outstanding_bat_ogm_packet+0x731/0x840 net/batman-adv/bat_iv_ogm.c:1711
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page+0x32/0x2e0 mm/page_alloc.c:2429
 discard_slab mm/slub.c:2122 [inline]
 __unfreeze_partials+0x1cf/0x210 mm/slub.c:2662
 put_cpu_partial+0x17c/0x250 mm/slub.c:2738
 __slab_free+0x31d/0x410 mm/slub.c:3686
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x143/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:305
 kasan_slab_alloc include/linux/kasan.h:188 [inline]
 slab_post_alloc_hook+0x6e/0x4d0 mm/slab.h:767
 slab_alloc_node mm/slub.c:3485 [inline]
 slab_alloc mm/slub.c:3493 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3500 [inline]
 kmem_cache_alloc+0x11e/0x2e0 mm/slub.c:3509
 getname_flags+0xbb/0x500 fs/namei.c:140
 do_sys_openat2+0xcb/0x1c0 fs/open.c:1413
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888020ec5f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888020ec5f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888020ec6000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                     ^
 ffff888020ec6080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888020ec6100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/17 02:44 linux-6.6.y c2603c511feb cfebc887 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: out-of-bounds Read in ext4_xattr_set_entry
* Struck through repros no longer work on HEAD.