KASAN: use-after-free Write in __xfrm_state_delete

Status: upstream: reported C repro on 2026/10/30 21:58
Reported-by: syzbot+2161064e86e23e71b49c@syzkaller.appspotmail.com
First crash: 13d, last: 5h40m
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/11/11 upstream (ToT) [unknown] C Failed due to an error; will retry later
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream KASAN: slab-use-after-free Write in __xfrm_state_delete net 22 syz, C done 4863 389d 472d 29/29 fixed on 2025/10/29 21:02
linux-6.6 KASAN: slab-use-after-free Write in __xfrm_state_delete origin:lts-only 22 syz inconclusive 10 413d 441d 0/2 upstream: reported syz repro on 2025/08/29 09:56

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in __hlist_del include/linux/list.h:906 [inline]
BUG: KASAN: use-after-free in hlist_del_init_rcu include/linux/rculist.h:184 [inline]
BUG: KASAN: use-after-free in __xfrm_state_delete+0x3db/0x940 net/xfrm/xfrm_state.c:700
Write of size 8 at addr ffff888028832190 by task kworker/u4:4/77

CPU: 1 PID: 77 Comm: kworker/u4:4 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
Workqueue: netns cleanup_net
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x24e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 __hlist_del include/linux/list.h:906 [inline]
 hlist_del_init_rcu include/linux/rculist.h:184 [inline]
 __xfrm_state_delete+0x3db/0x940 net/xfrm/xfrm_state.c:700
 xfrm_state_delete net/xfrm/xfrm_state.c:725 [inline]
 xfrm_state_flush+0x445/0x760 net/xfrm/xfrm_state.c:808
 xfrm6_tunnel_net_exit+0x38/0xf0 net/ipv6/xfrm6_tunnel.c:337
 ops_exit_list net/core/net_namespace.c:172 [inline]
 cleanup_net+0x703/0xba0 net/core/net_namespace.c:640
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>

Allocated by task 4328:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8e/0xa0 mm/kasan/common.c:384
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 __do_kmalloc_node mm/slab_common.c:936 [inline]
 __kmalloc+0xb3/0x240 mm/slab_common.c:949
 xfrm_hash_resize+0x84/0xff0 net/xfrm/xfrm_state.c:156
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

Freed by task 4328:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4b/0x70 mm/kasan/common.c:53
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:516
 ____kasan_slab_free+0x126/0x1f0 mm/kasan/common.c:237
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1735 [inline]
 slab_free_freelist_hook+0x133/0x1b0 mm/slub.c:1761
 slab_free mm/slub.c:3694 [inline]
 __kmem_cache_free+0xb6/0x200 mm/slub.c:3707
 xfrm_hash_resize+0xdce/0xff0 net/xfrm/xfrm_state.c:198
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

The buggy address belongs to the object at ffff888028832000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 400 bytes inside of
 4096-byte region [ffff888028832000, ffff888028833000)

The buggy address belongs to the physical page:
page:ffffea0000a20c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x28830
head:ffffea0000a20c00 order:3 compound_mapcount:0 compound_pincount:0
flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffffea0001d7ce00 dead000000000002 ffff888018442140
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 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 4411, tgid 4411 (syz-executor), ts 72708701681, free_ts 72640705340
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2560
 prep_new_page mm/page_alloc.c:2567 [inline]
 get_page_from_freelist+0x206b/0x2180 mm/page_alloc.c:4358
 __alloc_pages+0x1ec/0x4f0 mm/page_alloc.c:5658
 alloc_slab_page+0x5d/0x180 mm/slub.c:1805
 allocate_slab mm/slub.c:1950 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2003
 ___slab_alloc+0xbc5/0x1240 mm/slub.c:3161
 __slab_alloc mm/slub.c:3247 [inline]
 slab_alloc_node mm/slub.c:3332 [inline]
 __kmem_cache_alloc_node+0x126/0x270 mm/slub.c:3405
 __do_kmalloc_node mm/slab_common.c:935 [inline]
 __kmalloc+0xa3/0x240 mm/slab_common.c:949
 kmalloc include/linux/slab.h:568 [inline]
 tomoyo_realpath_from_path+0xe2/0x5c0 security/tomoyo/realpath.c:251
 tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
 tomoyo_check_open_permission+0x212/0x440 security/tomoyo/file.c:771
 security_file_open+0x5e/0xa0 security/security.c:1685
 do_dentry_open+0x2fd/0x10b0 fs/open.c:869
 do_open fs/namei.c:3677 [inline]
 path_openat+0x2674/0x2f10 fs/namei.c:3838
 do_filp_open+0x1ee/0x420 fs/namei.c:3865
 do_sys_openat2+0x14b/0x4f0 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __x64_sys_openat+0x135/0x160 fs/open.c:1347
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1487 [inline]
 free_pcp_prepare mm/page_alloc.c:1537 [inline]
 free_unref_page_prepare+0x8e5/0x9e0 mm/page_alloc.c:3414
 free_unref_page+0x2e/0x3f0 mm/page_alloc.c:3509
 free_slab mm/slub.c:2042 [inline]
 discard_slab mm/slub.c:2048 [inline]
 __unfreeze_partials+0x188/0x1e0 mm/slub.c:2598
 put_cpu_partial+0x17c/0x250 mm/slub.c:2674
 qlink_free mm/kasan/quarantine.c:166 [inline]
 qlist_free_all+0x76/0xe0 mm/kasan/quarantine.c:185
 kasan_quarantine_reduce+0x144/0x160 mm/kasan/quarantine.c:292
 __kasan_slab_alloc+0x1e/0x80 mm/kasan/common.c:306
 kasan_slab_alloc include/linux/kasan.h:201 [inline]
 slab_post_alloc_hook+0x4b/0x490 mm/slab.h:742
 slab_alloc_node mm/slub.c:3366 [inline]
 slab_alloc mm/slub.c:3374 [inline]
 __kmem_cache_alloc_lru mm/slub.c:3381 [inline]
 kmem_cache_alloc+0x18b/0x2f0 mm/slub.c:3390
 getname_kernel+0x56/0x2f0 fs/namei.c:227
 kern_path+0x19/0x50 fs/namei.c:2656
 tomoyo_mount_acl security/tomoyo/mount.c:136 [inline]
 tomoyo_mount_permission+0x787/0x9b0 security/tomoyo/mount.c:237
 security_sb_mount+0x83/0xb0 security/security.c:997
 path_mount+0xb8/0xfb0 fs/namespace.c:3404
 do_mount fs/namespace.c:3475 [inline]
 __do_sys_mount fs/namespace.c:3683 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3660
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76

Memory state around the buggy address:
 ffff888028832080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028832100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888028832180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888028832200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888028832280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (39):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/11/08 04:24 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 03:30 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 02:30 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/02 07:39 linux-6.1.y 08889840163e 25a0ae84 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/13 11:51 linux-6.1.y c75b0cf0982c be5d1971 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/10 16:02 linux-6.1.y c75b0cf0982c d3056657 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 19:23 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 19:19 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:58 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:57 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:56 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:51 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:50 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:46 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:46 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:42 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:41 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:37 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/08 01:35 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/07 10:19 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/07 10:17 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/06 20:02 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/03 06:24 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/03 06:24 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/02 09:43 linux-6.1.y 08889840163e 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/02 09:42 linux-6.1.y 08889840163e 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/01 12:59 linux-6.1.y 08889840163e 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/10/31 04:30 linux-6.1.y 08889840163e 0ec395f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan KASAN: use-after-free Write in __xfrm_state_delete
2026/11/10 21:46 linux-6.1.y c75b0cf0982c d3056657 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/10 08:09 linux-6.1.y c75b0cf0982c 70ec0380 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/09 04:36 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/09 03:00 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/09 01:44 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/03 17:16 linux-6.1.y 08889840163e e2d35131 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/02 15:38 linux-6.1.y 08889840163e 6969b601 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/02 06:28 linux-6.1.y 08889840163e 25a0ae84 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/10/30 21:58 linux-6.1.y 08889840163e 0ec395f8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: use-after-free Write in __xfrm_state_delete
2026/11/09 19:19 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: slab-out-of-bounds Write in __xfrm_state_delete
2026/11/07 06:10 linux-6.1.y c75b0cf0982c 5cecaf1f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: slab-out-of-bounds Write in __xfrm_state_delete
* Struck through repros no longer work on HEAD.