KASAN: slab-use-after-free Read in __xfrm_decode_session (2)

Status: auto-obsoleted due to no activity on 2026/02/17 15:57
Reported-by: syzbot+8e7802a7fb07f3b89273@syzkaller.appspotmail.com
First crash: 255d, last: 255d
▶ ▼ Similar bugs (12)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.6 KASAN: slab-use-after-free Read in __xfrm_decode_session 19 19 365d 386d 0/2 auto-obsoleted due to no activity on 2025/10/01 05:45
upstream KMSAN: uninit-value in __xfrm_decode_session (4) net 19 C 8 1005d 1052d 0/29 closed as invalid on 2023/12/14 11:46
linux-5.15 KASAN: slab-out-of-bounds Read in __xfrm_decode_session (3) origin:lts-only 19 C error 11 39d 102d 0/3 upstream: reported C repro on 2026/04/11 21:07
linux-6.1 KASAN: use-after-free Read in __xfrm_decode_session (2) origin:lts-only 19 C inconclusive 9 239d 449d 0/3 upstream: reported C repro on 2025/04/30 13:03
upstream KASAN: slab-out-of-bounds Read in __xfrm_decode_session (2) net 19 7 1690d 1927d 0/29 auto-closed as invalid on 2022/04/04 17:22
upstream KMSAN: kernel-infoleak in copyout (2) net 17 C 6723 1141d 2309d 22/29 fixed on 2023/06/08 14:41
linux-5.15 KASAN: slab-out-of-bounds Read in __xfrm_decode_session origin:upstream 19 C error 7 987d 1174d 0/3 auto-obsoleted due to no activity on 2024/02/16 23:16
upstream KMSAN: kernel-infoleak in _copy_to_iter (7) net 21 C 138977 1245d 1597d 22/29 fixed on 2023/02/24 13:50
linux-6.6 KASAN: slab-out-of-bounds Read in __xfrm_decode_session origin:lts-only 17 C error 1 122d 123d 0/2 upstream: reported C repro on 2026/03/22 10:21
linux-6.1 KASAN: slab-out-of-bounds Read in __xfrm_decode_session 17 1 574d 574d 0/3 auto-obsoleted due to no activity on 2025/04/05 09:29
linux-5.15 KASAN: slab-out-of-bounds Read in __xfrm_decode_session (2) 19 4 352d 480d 0/3 auto-obsoleted due to no activity on 2025/11/13 13:37
linux-6.1 KASAN: use-after-free Read in __xfrm_decode_session 19 4 1033d 1165d 0/3 auto-obsoleted due to no activity on 2024/01/01 21:03

Sample crash report:
==================================================================
BUG: KASAN: slab-use-after-free in decode_session6 net/xfrm/xfrm_policy.c:3494 [inline]
BUG: KASAN: slab-use-after-free in __xfrm_decode_session+0x18d7/0x20a0 net/xfrm/xfrm_policy.c:3600
Read of size 1 at addr ffff88805703b0e5 by task syz.2.2347/12205

CPU: 1 PID: 12205 Comm: syz.2.2347 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 decode_session6 net/xfrm/xfrm_policy.c:3494 [inline]
 __xfrm_decode_session+0x18d7/0x20a0 net/xfrm/xfrm_policy.c:3600
 xfrm_decode_session_reverse include/net/xfrm.h:1243 [inline]
 icmpv6_route_lookup+0x358/0x590 net/ipv6/icmp.c:392
 icmp6_send+0x106a/0x1990 net/ipv6/icmp.c:604
 __icmpv6_send include/linux/icmpv6.h:28 [inline]
 icmpv6_send include/linux/icmpv6.h:49 [inline]
 ip6_link_failure+0x3b/0x4c0 net/ipv6/route.c:2825
 dst_link_failure include/net/dst.h:437 [inline]
 ip6_tnl_xmit+0xdf7/0x2a30 net/ipv6/ip6_tunnel.c:1282
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1398 [inline]
 ip6_tnl_start_xmit+0xc10/0x1140 net/ipv6/ip6_tunnel.c:1446
 __netdev_start_xmit include/linux/netdevice.h:4943 [inline]
 netdev_start_xmit include/linux/netdevice.h:4957 [inline]
 xmit_one net/core/dev.c:3619 [inline]
 dev_hard_start_xmit+0x246/0x740 net/core/dev.c:3635
 sch_direct_xmit+0x252/0x4a0 net/sched/sch_generic.c:342
 qdisc_restart net/sched/sch_generic.c:407 [inline]
 __qdisc_run+0xab2/0x1570 net/sched/sch_generic.c:415
 __dev_xmit_skb net/core/dev.c:3919 [inline]
 __dev_queue_xmit+0xf02/0x35a0 net/core/dev.c:4391
 neigh_output include/net/neighbour.h:543 [inline]
 ip6_finish_output2+0xe2e/0x1650 net/ipv6/ip6_output.c:141
 ip6_fragment+0x13c5/0x1f90 net/ipv6/ip6_output.c:1023
 dst_output include/net/dst.h:467 [inline]
 NF_HOOK include/linux/netfilter.h:304 [inline]
 ip6_xmit+0x10aa/0x1840 net/ipv6/ip6_output.c:360
 sctp_v6_xmit+0x9e3/0x1230 net/sctp/ipv6.c:250
 sctp_packet_transmit+0x2488/0x2a30 net/sctp/output.c:653
 sctp_packet_singleton+0x234/0x330 net/sctp/outqueue.c:783
 sctp_outq_flush_ctrl net/sctp/outqueue.c:914 [inline]
 sctp_outq_flush+0x4f1/0x3100 net/sctp/outqueue.c:1212
 sctp_cmd_interpreter net/sctp/sm_sideeffect.c:-1 [inline]
 sctp_side_effects net/sctp/sm_sideeffect.c:1198 [inline]
 sctp_do_sm+0x52d6/0x59a0 net/sctp/sm_sideeffect.c:1169
 sctp_primitive_ASSOCIATE+0x95/0xc0 net/sctp/primitive.c:73
 __sctp_connect+0x92f/0xd20 net/sctp/socket.c:1234
 __sctp_setsockopt_connectx net/sctp/socket.c:1336 [inline]
 sctp_getsockopt_connectx3+0x2c7/0x440 net/sctp/socket.c:1421
 sctp_getsockopt+0x986/0xb60 net/sctp/socket.c:8128
 do_sock_getsockopt+0x368/0x440 net/socket.c:2384
 __sys_getsockopt net/socket.c:2413 [inline]
 __do_sys_getsockopt net/socket.c:2423 [inline]
 __se_sys_getsockopt net/socket.c:2420 [inline]
 __x64_sys_getsockopt+0x1d6/0x280 net/socket.c:2420
 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: 0033:0x7f5ff418f6c9
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:00007f5ff509b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000037
RAX: ffffffffffffffda RBX: 00007f5ff43e5fa0 RCX: 00007f5ff418f6c9
RDX: 000000000000006f RSI: 0000000000000084 RDI: 0000000000000004
RBP: 00007f5ff4211f91 R08: 0000200000000480 R09: 0000000000000000
R10: 00002000000001c0 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5ff43e6038 R14: 00007f5ff43e5fa0 R15: 00007ffeda3b5b58
 </TASK>

Allocated by task 12128:
 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
 kmalloc_reserve+0x117/0x260 net/core/skbuff.c:581
 pskb_expand_head+0x185/0x1230 net/core/skbuff.c:2099
 netlink_trim+0x180/0x220 net/netlink/af_netlink.c:1301
 netlink_broadcast_filtered+0x80/0x1110 net/netlink/af_netlink.c:1515
 netlink_broadcast net/netlink/af_netlink.c:1560 [inline]
 nlmsg_multicast include/net/netlink.h:1090 [inline]
 nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2588
 rtnl_notify net/core/rtnetlink.c:800 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:4093 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:4109 [inline]
 rtnetlink_event+0x224/0x260 net/core/rtnetlink.c:6523
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 netdev_features_change net/core/dev.c:1389 [inline]
 netdev_change_features+0x8e/0xc0 net/core/dev.c:9983
 team_add_slave+0x1dd5/0x2660 drivers/net/team/team.c:1987
 do_set_master net/core/rtnetlink.c:2706 [inline]
 do_setlink+0xe14/0x3fb0 net/core/rtnetlink.c:2912
 __rtnl_newlink net/core/rtnetlink.c:3703 [inline]
 rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 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

Freed by task 12128:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x2e/0x50 mm/kasan/generic.c:522
 ____kasan_slab_free+0x126/0x1e0 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:164 [inline]
 slab_free_hook mm/slub.c:1811 [inline]
 slab_free_freelist_hook+0x130/0x1b0 mm/slub.c:1837
 slab_free mm/slub.c:3830 [inline]
 __kmem_cache_free+0xba/0x1f0 mm/slub.c:3843
 skb_kfree_head net/core/skbuff.c:945 [inline]
 skb_free_head net/core/skbuff.c:957 [inline]
 skb_release_data+0x634/0x800 net/core/skbuff.c:987
 skb_release_all net/core/skbuff.c:1053 [inline]
 __kfree_skb net/core/skbuff.c:1067 [inline]
 consume_skb+0xb2/0x110 net/core/skbuff.c:1283
 netlink_broadcast_filtered+0x101c/0x1110 net/netlink/af_netlink.c:1538
 netlink_broadcast net/netlink/af_netlink.c:1560 [inline]
 nlmsg_multicast include/net/netlink.h:1090 [inline]
 nlmsg_notify+0xf0/0x1a0 net/netlink/af_netlink.c:2588
 rtnl_notify net/core/rtnetlink.c:800 [inline]
 rtmsg_ifinfo_send net/core/rtnetlink.c:4093 [inline]
 rtmsg_ifinfo_event net/core/rtnetlink.c:4109 [inline]
 rtnetlink_event+0x224/0x260 net/core/rtnetlink.c:6523
 notifier_call_chain+0x197/0x390 kernel/notifier.c:93
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 netdev_features_change net/core/dev.c:1389 [inline]
 netdev_change_features+0x8e/0xc0 net/core/dev.c:9983
 team_add_slave+0x1dd5/0x2660 drivers/net/team/team.c:1987
 do_set_master net/core/rtnetlink.c:2706 [inline]
 do_setlink+0xe14/0x3fb0 net/core/rtnetlink.c:2912
 __rtnl_newlink net/core/rtnetlink.c:3703 [inline]
 rtnl_newlink+0x175b/0x2020 net/core/rtnetlink.c:3750
 rtnetlink_rcv_msg+0x7c7/0xf10 net/core/rtnetlink.c:6472
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0xde/0xf0 net/socket.c:2209
 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

The buggy address belongs to the object at ffff88805703b000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 229 bytes inside of
 freed 2048-byte region [ffff88805703b000, ffff88805703b800)

The buggy address belongs to the physical page:
page:ffffea00015c0e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x57038
head:ffffea00015c0e00 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 ffff888017842000 ffffea0000ae5400 dead000000000002
raw: 0000000000000000 0000000080080008 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 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 11510, tgid 11509 (syz.2.2069), ts 330136975073, free_ts 327727965369
 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:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2e0 mm/slub.c:2081
 ___slab_alloc+0xc6d/0x1300 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x1a2/0x260 mm/slub.c:3534
 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 copy_verifier_state+0x8b1/0xd20 kernel/bpf/verifier.c:1792
 push_stack+0x1b9/0x500 kernel/bpf/verifier.c:2060
 check_cond_jmp_op+0xdd0/0x2680 kernel/bpf/verifier.c:14635
 do_check+0x672e/0xdbe0 kernel/bpf/verifier.c:17358
 do_check_common+0xadb/0x13e0 kernel/bpf/verifier.c:19704
 do_check_main kernel/bpf/verifier.c:19767 [inline]
 bpf_check+0x649f/0xe970 kernel/bpf/verifier.c:20435
 bpf_prog_load+0x11cb/0x16d0 kernel/bpf/syscall.c:2750
 __sys_bpf+0x55a/0x800 kernel/bpf/syscall.c:5473
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
 napi_frag_unref include/linux/skbuff.h:3507 [inline]
 skb_release_data+0x49a/0x800 net/core/skbuff.c:981
 skb_release_all net/core/skbuff.c:1053 [inline]
 __kfree_skb net/core/skbuff.c:1067 [inline]
 napi_consume_skb+0x123/0x200 net/core/skbuff.c:1357
 skb_defer_free_flush net/core/dev.c:6733 [inline]
 net_rx_action+0x41f/0xbf0 net/core/dev.c:6796
 handle_softirqs+0x280/0x820 kernel/softirq.c:578
 run_ksoftirqd+0x9c/0xf0 kernel/softirq.c:950
 smpboot_thread_fn+0x635/0xa00 kernel/smpboot.c:164
 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

Memory state around the buggy address:
 ffff88805703af80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805703b000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff88805703b080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                       ^
 ffff88805703b100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805703b180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/09 15:56 linux-6.6.y 0a805b6ea8cd 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan KASAN: slab-use-after-free Read in __xfrm_decode_session
* Struck through repros no longer work on HEAD.