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

Status: auto-obsoleted due to no activity on 2025/04/05 09:29
Reported-by: syzbot+8d0bf962e4fedb1613b1@syzkaller.appspotmail.com
First crash: 574d, last: 574d
▶ ▼ Similar bugs (13)
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
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
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-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
upstream KASAN: slab-out-of-bounds Read in __xfrm_decode_session net 17 20 2143d 2428d 0/29 auto-closed as invalid on 2021/01/07 14:52
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
linux-6.6 KASAN: slab-use-after-free Read in __xfrm_decode_session (2) 19 1 256d 256d 0/2 auto-obsoleted due to no activity on 2026/02/17 15:57
upstream KMSAN: kernel-infoleak in _copy_to_iter (7) net 21 C 138977 1245d 1597d 22/29 fixed on 2023/02/24 13:50
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

Sample crash report:
==================================================================
BUG: KASAN: slab-out-of-bounds in decode_session6 net/xfrm/xfrm_policy.c:3412 [inline]
BUG: KASAN: slab-out-of-bounds in __xfrm_decode_session+0x1670/0x1e5c net/xfrm/xfrm_policy.c:3518
Read of size 1 at addr ffff0000da2bf741 by task syz.3.32/4526

CPU: 0 PID: 4526 Comm: syz.3.32 Tainted: G        W          6.1.121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0x174/0x4c0 mm/kasan/report.c:427
 kasan_report+0xd4/0x130 mm/kasan/report.c:531
 __asan_report_load1_noabort+0x2c/0x38 mm/kasan/report_generic.c:348
 decode_session6 net/xfrm/xfrm_policy.c:3412 [inline]
 __xfrm_decode_session+0x1670/0x1e5c net/xfrm/xfrm_policy.c:3518
 xfrm_decode_session_reverse include/net/xfrm.h:1184 [inline]
 icmpv6_route_lookup+0x398/0x558 net/ipv6/icmp.c:394
 icmp6_send+0xe18/0x1b8c net/ipv6/icmp.c:603
 __icmpv6_send include/linux/icmpv6.h:28 [inline]
 icmpv6_send include/linux/icmpv6.h:49 [inline]
 ip6_link_failure+0x44/0x4a8 net/ipv6/route.c:2793
 dst_link_failure include/net/dst.h:423 [inline]
 ip6_tnl_xmit+0x1010/0x2698 net/ipv6/ip6_tunnel.c:1284
 ipxip6_tnl_xmit net/ipv6/ip6_tunnel.c:1400 [inline]
 ip6_tnl_start_xmit+0xda8/0x142c net/ipv6/ip6_tunnel.c:1449
 __netdev_start_xmit include/linux/netdevice.h:4888 [inline]
 netdev_start_xmit include/linux/netdevice.h:4902 [inline]
 xmit_one net/core/dev.c:3627 [inline]
 dev_hard_start_xmit+0x25c/0x9a4 net/core/dev.c:3643
 sch_direct_xmit+0x234/0x548 net/sched/sch_generic.c:342
 qdisc_restart net/sched/sch_generic.c:407 [inline]
 __qdisc_run+0x904/0x239c net/sched/sch_generic.c:415
 __dev_xmit_skb net/core/dev.c:3925 [inline]
 __dev_queue_xmit+0xcac/0x34d0 net/core/dev.c:4267
 dev_queue_xmit include/linux/netdevice.h:3043 [inline]
 neigh_connected_output+0x344/0x3d4 net/core/neighbour.c:1592
 neigh_output include/net/neighbour.h:544 [inline]
 ip6_finish_output2+0xdb8/0x1b54 net/ipv6/ip6_output.c:138
 ip6_fragment+0x1b74/0x2a80 net/ipv6/ip6_output.c:960
 __ip6_finish_output net/ipv6/ip6_output.c:203 [inline]
 ip6_finish_output+0x444/0x940 net/ipv6/ip6_output.c:216
 NF_HOOK_COND include/linux/netfilter.h:291 [inline]
 ip6_output+0x274/0x594 net/ipv6/ip6_output.c:237
 dst_output include/net/dst.h:444 [inline]
 ip6_local_out+0x120/0x160 net/ipv6/output_core.c:161
 ip6_send_skb+0x19c/0x570 net/ipv6/ip6_output.c:2008
 udp_v6_send_skb+0xa0c/0x1760 net/ipv6/udp.c:1305
 udpv6_sendmsg+0x19d8/0x28c8 net/ipv6/udp.c:1600
 inet6_sendmsg+0xb4/0xd8 net/ipv6/af_inet6.c:668
 sock_sendmsg_nosec net/socket.c:718 [inline]
 __sock_sendmsg net/socket.c:730 [inline]
 ____sys_sendmsg+0x55c/0x848 net/socket.c:2519
 ___sys_sendmsg net/socket.c:2573 [inline]
 __sys_sendmsg+0x26c/0x33c net/socket.c:2602
 __do_sys_sendmsg net/socket.c:2611 [inline]
 __se_sys_sendmsg net/socket.c:2609 [inline]
 __arm64_sys_sendmsg+0x80/0x94 net/socket.c:2609
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

Allocated by task 4332:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x80 mm/kasan/common.c:52
 kasan_save_alloc_info+0x24/0x30 mm/kasan/generic.c:505
 ____kasan_kmalloc mm/kasan/common.c:374 [inline]
 __kasan_kmalloc+0xac/0xc4 mm/kasan/common.c:383
 kasan_kmalloc include/linux/kasan.h:211 [inline]
 kmalloc_trace+0x7c/0x94 mm/slab_common.c:1031
 kmalloc include/linux/slab.h:563 [inline]
 kzalloc include/linux/slab.h:699 [inline]
 snmp6_alloc_dev net/ipv6/addrconf.c:354 [inline]
 ipv6_add_dev+0x530/0xfd0 net/ipv6/addrconf.c:404
 addrconf_notify+0x4fc/0xc94 net/ipv6/addrconf.c:3598
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0xd4/0x164 kernel/notifier.c:455
 call_netdevice_notifiers_info net/core/dev.c:1970 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2008 [inline]
 call_netdevice_notifiers+0x138/0x1b8 net/core/dev.c:2022
 register_netdevice+0x117c/0x150c net/core/dev.c:10192
 __ip_tunnel_create+0x23c/0x304 net/ipv4/ip_tunnel.c:267
 ip_tunnel_init_net+0x1e0/0x5b0 net/ipv4/ip_tunnel.c:1100
 ipgre_tap_init_net+0x38/0x48 net/ipv4/ip_gre.c:1700
 ops_init+0x2e4/0x54c net/core/net_namespace.c:138
 setup_net+0x424/0xaac net/core/net_namespace.c:335
 copy_net_ns+0x2ec/0x58c net/core/net_namespace.c:498
 create_new_namespaces+0x344/0x614 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0x108/0x158 kernel/nsproxy.c:226
 ksys_unshare+0x424/0x7e4 kernel/fork.c:3201
 __do_sys_unshare kernel/fork.c:3272 [inline]
 __se_sys_unshare kernel/fork.c:3270 [inline]
 __arm64_sys_unshare+0x3c/0x50 kernel/fork.c:3270
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2bc arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x13c arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x168 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the object at ffff0000da2be000
 which belongs to the cache kmalloc-cg-4k of size 4096
The buggy address is located 1857 bytes to the right of
 4096-byte region [ffff0000da2be000, ffff0000da2bf000)

The buggy address belongs to the physical page:
page:00000000cb6f133d refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x11a2b8
head:00000000cb6f133d order:3 compound_mapcount:0 compound_pincount:0
flags: 0x5ffc00000010200(slab|head|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000010200 0000000000000000 dead000000000122 ffff0000c0003500
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000da2bf600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000da2bf680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff0000da2bf700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff0000da2bf780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff0000da2bf800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/26 09:29 linux-6.1.y 29f02ec58a94 444551c4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 KASAN: slab-out-of-bounds Read in __xfrm_decode_session
* Struck through repros no longer work on HEAD.