KASAN: use-after-free Read in l2tp_tunnel_get_session

Status: premoderation: reported on 2026/07/05 05:21
Reported-by: syzbot+525f2200000ed7667792@syzkaller.appspotmail.com
First crash: 76d, last: 6d11h
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 KASAN: use-after-free Read in l2tp_tunnel_get_session 19 5 7h19m 58d 0/2 premoderation: reported on 2026/07/23 21:14
android-5-15 KASAN: use-after-free Read in l2tp_tunnel_get_session 19 4 56d 85d 0/2 premoderation: reported on 2026/06/26 07:57

Sample crash report:
==================================================================
BUG: KASAN: use-after-free in l2tp_tunnel_get_session+0xcd/0x170 net/l2tp/l2tp_core.c:270
Read of size 4 at addr ffff88810df9b418 by task syz.8.673/3633

CPU: 0 PID: 3633 Comm: syz.8.673 Tainted: G        W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 __dump_stack+0x21/0x24 lib/dump_stack.c:77
 dump_stack_lvl+0x1a7/0x208 lib/dump_stack.c:118
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:435 [inline]
 kasan_report+0x100/0x140 mm/kasan/report.c:452
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 l2tp_tunnel_get_session+0xcd/0x170 net/l2tp/l2tp_core.c:270
 l2tp_udp_recv_core net/l2tp/l2tp_core.c:875 [inline]
 l2tp_udp_encap_recv+0x318/0x7e0 net/l2tp/l2tp_core.c:929
 udpv6_queue_rcv_one_skb+0x11ea/0x1350 net/ipv6/udp.c:712
 udpv6_queue_rcv_skb+0x470/0x680 net/ipv6/udp.c:770
 udp6_unicast_rcv_skb+0x1e0/0x310 net/ipv6/udp.c:912
 __udp6_lib_rcv+0xa45/0xe10 net/ipv6/udp.c:996
 udpv6_rcv+0x21/0x30 net/ipv6/udp.c:1098
 ip6_protocol_deliver_rcu+0x8ad/0x1380 net/ipv6/ip6_input.c:427
 ip6_input_finish net/ipv6/ip6_input.c:468 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip6_input+0xda/0x210 net/ipv6/ip6_input.c:477
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x18c/0x360 net/ipv6/ip6_input.c:80
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ipv6_rcv+0xf0/0x230 net/ipv6/ip6_input.c:301
 __netif_receive_skb_one_core net/core/dev.c:5413 [inline]
 __netif_receive_skb+0xc8/0x280 net/core/dev.c:5527
 netif_receive_skb_internal net/core/dev.c:5632 [inline]
 netif_receive_skb+0x9b/0x3e0 net/core/dev.c:5691
 tun_rx_batched+0x600/0x750 drivers/net/tun.c:-1
 tun_get_user+0x270e/0x31c0 drivers/net/tun.c:2026
 tun_chr_write_iter+0x1c1/0x270 drivers/net/tun.c:2059
 call_write_iter include/linux/fs.h:2072 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 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+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7f2fcfe98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f7f2e6f1fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7f2e6f26c0 RCX: 00007f7f2fcfe98e
RDX: 000000000000004c RSI: 0000200000000300 RDI: 00000000000000c8
RBP: 00007f7f2fdd503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f2ffc64e8 R14: 00007f7f2ffc6450 R15: 00007ffe64963b88

Allocated by task 3595:
 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 mm/kasan/common.c:509 [inline]
 __kasan_kmalloc+0xd4/0x100 mm/kasan/common.c:518
 kasan_kmalloc include/linux/kasan.h:254 [inline]
 __kmalloc+0x19f/0x330 mm/slub.c:4038
 kmalloc include/linux/slab.h:560 [inline]
 kzalloc include/linux/slab.h:667 [inline]
 l2tp_session_create+0x39/0xb60 net/l2tp/l2tp_core.c:1616
 pppol2tp_connect+0xbf5/0x1640 net/l2tp/l2tp_ppp.c:772
 __sys_connect_file net/socket.c:1867 [inline]
 __sys_connect+0x3ce/0x450 net/socket.c:1884
 __do_sys_connect net/socket.c:1894 [inline]
 __se_sys_connect net/socket.c:1891 [inline]
 __x64_sys_connect+0x7a/0x90 net/socket.c:1891
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Freed by task 3631:
 kasan_save_stack mm/kasan/common.c:38 [inline]
 kasan_set_track+0x4a/0x70 mm/kasan/common.c:45
 kasan_set_free_info+0x23/0x40 mm/kasan/generic.c:370
 ____kasan_slab_free+0x125/0x160 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:1600 [inline]
 slab_free_freelist_hook+0xc5/0x190 mm/slub.c:1626
 slab_free mm/slub.c:3208 [inline]
 kfree+0xc0/0x270 mm/slub.c:4196
 l2tp_session_free net/l2tp/l2tp_core.c:168 [inline]
 l2tp_session_put+0xb2/0x1a0 net/l2tp/l2tp_core.c:193
 pppol2tp_ioctl+0x748/0x960 net/l2tp/l2tp_ppp.c:-1
 pppox_ioctl+0x1e4/0x320 drivers/net/ppp/pppox.c:93
 sock_do_ioctl+0xda/0x380 net/socket.c:1068
 sock_ioctl+0x472/0x740 net/socket.c:1208
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0x121/0x1a0 fs/ioctl.c:739
 __x64_sys_ioctl+0x7b/0x90 fs/ioctl.c:739
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Last potentially related work creation:
 kasan_save_stack+0x3a/0x60 mm/kasan/common.c:38
 __kasan_record_aux_stack+0xd2/0x100 mm/kasan/generic.c:348
 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:358
 __call_rcu kernel/rcu/tree.c:2980 [inline]
 call_rcu+0x11a/0x1090 kernel/rcu/tree.c:3054
 fib6_info_release include/net/ip6_fib.h:346 [inline]
 __ip6_del_rt+0xf5/0x150 net/ipv6/route.c:3794
 ip6_del_rt+0xbe/0x110 net/ipv6/route.c:3805
 __ipv6_ifa_notify+0x872/0xe70 net/ipv6/addrconf.c:6196
 addrconf_ifdown+0xdb1/0x1890 net/ipv6/addrconf.c:3918
 addrconf_notify+0x3bd/0xea0 net/ipv6/addrconf.c:-1
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x90/0x100 kernel/notifier.c:410
 call_netdevice_notifiers_info net/core/dev.c:2052 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2064 [inline]
 call_netdevice_notifiers net/core/dev.c:2078 [inline]
 dev_close_many+0x328/0x4d0 net/core/dev.c:1653
 unregister_netdevice_many+0x477/0x19f0 net/core/dev.c:10755
 default_device_exit_batch+0x35e/0x3c0 net/core/dev.c:11298
 ops_exit_list net/core/net_namespace.c:190 [inline]
 cleanup_net+0x5fe/0xb80 net/core/net_namespace.c:609
 process_one_work+0x6fd/0xbc0 kernel/workqueue.c:2301
 worker_thread+0xa8e/0x13c0 kernel/workqueue.c:2447
 kthread+0x324/0x3b0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298

The buggy address belongs to the object at ffff88810df9b400
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 24 bytes inside of
 512-byte region [ffff88810df9b400, ffff88810df9b600)
The buggy address belongs to the page:
page:ffffea000437e600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10df98
head:ffffea000437e600 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x4000000000010200(slab|head)
raw: 4000000000010200 ffffea00049f6200 0000000200000002 ffff888100043080
raw: 0000000000000000 0000000000100010 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x1d20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 281, ts 26628868538, free_ts 26622477826
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2456 [inline]
 prep_new_page+0x176/0x190 mm/page_alloc.c:2462
 get_page_from_freelist+0x225f/0x23f0 mm/page_alloc.c:4254
 __alloc_pages_nodemask+0x29a/0x640 mm/page_alloc.c:5384
 alloc_slab_page mm/slub.c:-1 [inline]
 allocate_slab mm/slub.c:1813 [inline]
 new_slab+0x84/0x3f0 mm/slub.c:1874
 new_slab_objects mm/slub.c:2632 [inline]
 ___slab_alloc+0x2f8/0x4c0 mm/slub.c:2796
 __slab_alloc+0x63/0xa0 mm/slub.c:2836
 slab_alloc_node mm/slub.c:2918 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 __kmalloc_track_caller+0x1e4/0x310 mm/slub.c:4541
 __kmalloc_reserve net/core/skbuff.c:144 [inline]
 __alloc_skb+0xdc/0x520 net/core/skbuff.c:212
 alloc_skb include/linux/skbuff.h:1126 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1178 [inline]
 netlink_sendmsg+0x693/0xb70 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:652 [inline]
 __sock_sendmsg net/socket.c:664 [inline]
 __sys_sendto+0x467/0x620 net/socket.c:2007
 __do_sys_sendto net/socket.c:2019 [inline]
 __se_sys_sendto net/socket.c:2015 [inline]
 __x64_sys_sendto+0xe5/0x100 net/socket.c:2015
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1349 [inline]
 __free_pages_ok+0x80b/0x830 mm/page_alloc.c:1629
 free_the_page mm/page_alloc.c:5445 [inline]
 __free_pages+0xd8/0x390 mm/page_alloc.c:5454
 __free_slab+0xcf/0x190 mm/slub.c:1899
 free_slab mm/slub.c:1914 [inline]
 discard_slab mm/slub.c:1920 [inline]
 unfreeze_partials+0x150/0x180 mm/slub.c:2415
 put_cpu_partial+0xc1/0x180 mm/slub.c:2451
 __slab_free+0x2c9/0x3a0 mm/slub.c:3100
 do_slab_free mm/slub.c:3196 [inline]
 ___cache_free+0x10e/0x130 mm/slub.c:3215
 qlink_free+0x50/0x90 mm/kasan/quarantine.c:157
 qlist_free_all+0x5f/0xb0 mm/kasan/quarantine.c:176
 kasan_quarantine_reduce+0x14a/0x160 mm/kasan/quarantine.c:283
 __kasan_slab_alloc+0x2f/0xe0 mm/kasan/common.c:440
 kasan_slab_alloc include/linux/kasan.h:244 [inline]
 slab_post_alloc_hook+0x5d/0x2f0 mm/slab.h:580
 slab_alloc_node mm/slub.c:2952 [inline]
 slab_alloc mm/slub.c:2960 [inline]
 kmem_cache_alloc_trace+0x155/0x2e0 mm/slub.c:2977
 kmem_cache_alloc_node_trace include/linux/slab.h:443 [inline]
 kmalloc_node include/linux/slab.h:573 [inline]
 kzalloc_node include/linux/slab.h:678 [inline]
 __get_vm_area_node+0x113/0x450 mm/vmalloc.c:2092
 __vmalloc_node_range+0xe7/0x7a0 mm/vmalloc.c:2598
 __vmalloc_node mm/vmalloc.c:2689 [inline]
 vzalloc+0x78/0x90 mm/vmalloc.c:2742

Memory state around the buggy address:
 ffff88810df9b300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810df9b380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810df9b400: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffff88810df9b480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810df9b500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
------------[ cut here ]------------
refcount_t: addition on 0; use-after-free.
WARNING: CPU: 0 PID: 3633 at lib/refcount.c:25 refcount_warn_saturate+0x104/0x1a0 lib/refcount.c:25
Modules linked in:
CPU: 0 PID: 3633 Comm: syz.8.673 Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:refcount_warn_saturate+0x104/0x1a0 lib/refcount.c:25
Code: 04 01 48 c7 c7 00 54 40 85 e8 d8 60 3b 02 0f 0b eb df e8 bf 8e 26 ff c6 05 6d 73 82 04 01 48 c7 c7 40 53 40 85 e8 bc 60 3b 02 <0f> 0b eb c3 e8 a3 8e 26 ff c6 05 52 73 82 04 01 48 c7 c7 a0 53 40
RSP: 0018:ffffc90000f0f1f8 EFLAGS: 00010246
RAX: 4723e575597afc00 RBX: 0000000000000002 RCX: ffff88811c2f5000
RDX: 0000000000000000 RSI: 0000000000000401 RDI: 0000000000000000
RBP: ffffc90000f0f208 R08: ffffc90000f0eb87 R09: fffff520001e1da4
R10: dffffc0000000000 R11: fffff520001e1d71 R12: 0000000000000000
R13: dffffc0000000000 R14: 0000000000000002 R15: ffff88810df9b488
FS:  00007f7f2e6f26c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f2e711fd0 CR3: 000000012114e000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_add include/linux/refcount.h:-1 [inline]
 __refcount_inc include/linux/refcount.h:250 [inline]
 refcount_inc include/linux/refcount.h:267 [inline]
 l2tp_session_inc_refcount net/l2tp/l2tp_core.c:211 [inline]
 l2tp_tunnel_get_session+0x161/0x170 net/l2tp/l2tp_core.c:271
 l2tp_udp_recv_core net/l2tp/l2tp_core.c:875 [inline]
 l2tp_udp_encap_recv+0x318/0x7e0 net/l2tp/l2tp_core.c:929
 udpv6_queue_rcv_one_skb+0x11ea/0x1350 net/ipv6/udp.c:712
 udpv6_queue_rcv_skb+0x470/0x680 net/ipv6/udp.c:770
 udp6_unicast_rcv_skb+0x1e0/0x310 net/ipv6/udp.c:912
 __udp6_lib_rcv+0xa45/0xe10 net/ipv6/udp.c:996
 udpv6_rcv+0x21/0x30 net/ipv6/udp.c:1098
 ip6_protocol_deliver_rcu+0x8ad/0x1380 net/ipv6/ip6_input.c:427
 ip6_input_finish net/ipv6/ip6_input.c:468 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip6_input+0xda/0x210 net/ipv6/ip6_input.c:477
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x18c/0x360 net/ipv6/ip6_input.c:80
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ipv6_rcv+0xf0/0x230 net/ipv6/ip6_input.c:301
 __netif_receive_skb_one_core net/core/dev.c:5413 [inline]
 __netif_receive_skb+0xc8/0x280 net/core/dev.c:5527
 netif_receive_skb_internal net/core/dev.c:5632 [inline]
 netif_receive_skb+0x9b/0x3e0 net/core/dev.c:5691
 tun_rx_batched+0x600/0x750 drivers/net/tun.c:-1
 tun_get_user+0x270e/0x31c0 drivers/net/tun.c:2026
 tun_chr_write_iter+0x1c1/0x270 drivers/net/tun.c:2059
 call_write_iter include/linux/fs.h:2072 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 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+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7f2fcfe98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f7f2e6f1fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7f2e6f26c0 RCX: 00007f7f2fcfe98e
RDX: 000000000000004c RSI: 0000200000000300 RDI: 00000000000000c8
RBP: 00007f7f2fdd503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f2ffc64e8 R14: 00007f7f2ffc6450 R15: 00007ffe64963b88
---[ end trace 0396ef5a3006ce20 ]---
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 0 PID: 3633 at lib/refcount.c:28 refcount_warn_saturate+0x120/0x1a0 lib/refcount.c:28
Modules linked in:
CPU: 0 PID: 3633 Comm: syz.8.673 Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:refcount_warn_saturate+0x120/0x1a0 lib/refcount.c:28
Code: 04 01 48 c7 c7 40 53 40 85 e8 bc 60 3b 02 0f 0b eb c3 e8 a3 8e 26 ff c6 05 52 73 82 04 01 48 c7 c7 a0 53 40 85 e8 a0 60 3b 02 <0f> 0b eb a7 e8 87 8e 26 ff c6 05 33 73 82 04 01 48 c7 c7 c0 52 40
RSP: 0018:ffffc90000f0f208 EFLAGS: 00010246
RAX: 4723e575597afc00 RBX: 0000000000000003 RCX: ffff88811c2f5000
RDX: 0000000000000000 RSI: 0000000000000200 RDI: 0000000000000000
RBP: ffffc90000f0f218 R08: ffff8881f7027453 R09: 1ffff1103ee04e8a
R10: dffffc0000000000 R11: ffffed103ee04e8b R12: ffff888138f6007e
R13: 1ffff1102154f486 R14: 0000000000000003 R15: 00000000c0000000
FS:  00007f7f2e6f26c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f7f2e711fd0 CR3: 000000012114e000 CR4: 00000000003526b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __refcount_sub_and_test include/linux/refcount.h:283 [inline]
 __refcount_dec_and_test include/linux/refcount.h:315 [inline]
 refcount_dec_and_test include/linux/refcount.h:333 [inline]
 l2tp_session_put+0xcb/0x1a0 net/l2tp/l2tp_core.c:192
 l2tp_udp_recv_core net/l2tp/l2tp_core.c:893 [inline]
 l2tp_udp_encap_recv+0x555/0x7e0 net/l2tp/l2tp_core.c:929
 udpv6_queue_rcv_one_skb+0x11ea/0x1350 net/ipv6/udp.c:712
 udpv6_queue_rcv_skb+0x470/0x680 net/ipv6/udp.c:770
 udp6_unicast_rcv_skb+0x1e0/0x310 net/ipv6/udp.c:912
 __udp6_lib_rcv+0xa45/0xe10 net/ipv6/udp.c:996
 udpv6_rcv+0x21/0x30 net/ipv6/udp.c:1098
 ip6_protocol_deliver_rcu+0x8ad/0x1380 net/ipv6/ip6_input.c:427
 ip6_input_finish net/ipv6/ip6_input.c:468 [inline]
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ip6_input+0xda/0x210 net/ipv6/ip6_input.c:477
 dst_input include/net/dst.h:461 [inline]
 ip6_rcv_finish+0x18c/0x360 net/ipv6/ip6_input.c:80
 NF_HOOK include/linux/netfilter.h:299 [inline]
 ipv6_rcv+0xf0/0x230 net/ipv6/ip6_input.c:301
 __netif_receive_skb_one_core net/core/dev.c:5413 [inline]
 __netif_receive_skb+0xc8/0x280 net/core/dev.c:5527
 netif_receive_skb_internal net/core/dev.c:5632 [inline]
 netif_receive_skb+0x9b/0x3e0 net/core/dev.c:5691
 tun_rx_batched+0x600/0x750 drivers/net/tun.c:-1
 tun_get_user+0x270e/0x31c0 drivers/net/tun.c:2026
 tun_chr_write_iter+0x1c1/0x270 drivers/net/tun.c:2059
 call_write_iter include/linux/fs.h:2072 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 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+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f7f2fcfe98e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007f7f2e6f1fb8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7f2e6f26c0 RCX: 00007f7f2fcfe98e
RDX: 000000000000004c RSI: 0000200000000300 RDI: 00000000000000c8
RBP: 00007f7f2fdd503b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7f2ffc64e8 R14: 00007f7f2ffc6450 R15: 00007ffe64963b88
---[ end trace 0396ef5a3006ce21 ]---

Crashes (4):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/09/13 17:17 android13-5.10-lts 452567d1985b 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in l2tp_tunnel_get_session
2026/09/13 10:14 android13-5.10-lts 452567d1985b 70a60e12 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in l2tp_tunnel_get_session
2026/08/08 19:49 android13-5.10-lts 447db0046f21 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in l2tp_tunnel_get_session
2026/07/05 05:20 android13-5.10-lts 1bb06dbd8c78 fcece630 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 KASAN: use-after-free Read in l2tp_tunnel_get_session
* Struck through repros no longer work on HEAD.