KASAN: slab-use-after-free Read in sit_tunnel

ID	Workflow	Result	Correct	Bug	Created	Started	Finished	Revision	Error
f1ecce84-c02d-4059-a5e8-e7e75fe9179d	assessment-security		💥	KASAN: slab-use-after-free Read in sit_tunnel_xmit	2026/06/09 13:30	2026/06/09 13:30	2026/06/09 13:30	c36c07f6c1f2230a36374cbd22235f635e8f9284	failed to run ["git" "-c" "core.hooksPath=/dev/null" "fetch" "--force" "--tags" "5c96e23a32a280262291fe5d31d8f7dc6f666b47" "c93952cc0034dc491cf082d1df11e996513a53ed"]: exit status 128 error: insufficient permission for adding an object to repository database .git/objects fatal: failed to write object fatal: unpack-objects failed

Title	Replies (including bot)	Last reply
Re: [PATCH] ipv6: sit: reload inner IPv6 header after GSO offloads	1 (1)	2026/06/07 06:35
[syzbot] [net?] KASAN: slab-use-after-free Read in sit_tunnel_xmit	0 (1)	2026/06/07 06:33

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Re: [PATCH] ipv6: sit: reload inner IPv6 header after GSO offloads

1 (1)

2026/06/07 06:35

[syzbot] [net?] KASAN: slab-use-after-free Read in sit_tunnel_xmit

0 (1)

2026/06/07 06:33

================================================================== BUG: KASAN: slab-use-after-free in ipv6_get_dsfield include/net/dsfield.h:24 [inline] BUG: KASAN: slab-use-after-free in ipip6_tunnel_xmit net/ipv6/sit.c:1021 [inline] BUG: KASAN: slab-use-after-free in sit_tunnel_xmit+0x19b5/0x1b80 net/ipv6/sit.c:1072 Read of size 2 at addr ffff88801bba9760 by task syz.0.1430/10890 CPU: 0 UID: 0 PID: 10890 Comm: syz.0.1430 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: <TASK> dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_address_description+0x55/0x1e0 mm/kasan/report.c:378 print_report+0x58/0x70 mm/kasan/report.c:482 kasan_report+0x117/0x150 mm/kasan/report.c:595 ipv6_get_dsfield include/net/dsfield.h:24 [inline] ipip6_tunnel_xmit net/ipv6/sit.c:1021 [inline] sit_tunnel_xmit+0x19b5/0x1b80 net/ipv6/sit.c:1072 __netdev_start_xmit include/linux/netdevice.h:5368 [inline] netdev_start_xmit include/linux/netdevice.h:5377 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870 packet_snd net/packet/af_packet.c:3082 [inline] packet_sendmsg+0x3c81/0x4fb0 net/packet/af_packet.c:3114 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] __sys_sendto+0x672/0x710 net/socket.c:2265 __do_sys_sendto net/socket.c:2272 [inline] __se_sys_sendto net/socket.c:2268 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2268 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff06c39ce59 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ff06d1e8028 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00007ff06c615fa0 RCX: 00007ff06c39ce59 RDX: 000000000000fc13 RSI: 0000200000000280 RDI: 0000000000000005 RBP: 00007ff06c432d6f R08: 0000000000000000 R09: 000000000000002f R10: 0000000000000800 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ff06c616038 R14: 00007ff06c615fa0 R15: 00007ffe13a440e8 </TASK> Allocated by task 10890: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 unpoison_slab_object mm/kasan/common.c:340 [inline] __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4570 [inline] slab_alloc_node mm/slub.c:4899 [inline] kmem_cache_alloc_node_noprof+0x384/0x690 mm/slub.c:4951 kmalloc_reserve net/core/skbuff.c:613 [inline] __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713 alloc_skb include/linux/skbuff.h:1385 [inline] alloc_skb_with_frags+0xc8/0x760 net/core/skbuff.c:6766 sock_alloc_send_pskb+0x878/0x990 net/core/sock.c:3002 packet_alloc_skb net/packet/af_packet.c:2932 [inline] packet_snd net/packet/af_packet.c:3025 [inline] packet_sendmsg+0x315a/0x4fb0 net/packet/af_packet.c:3114 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] __sys_sendto+0x672/0x710 net/socket.c:2265 __do_sys_sendto net/socket.c:2272 [inline] __se_sys_sendto net/socket.c:2268 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2268 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 10890: kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2689 [inline] slab_free mm/slub.c:6251 [inline] kfree+0x1c5/0x640 mm/slub.c:6566 skb_kfree_head net/core/skbuff.c:1075 [inline] skb_free_head net/core/skbuff.c:1087 [inline] pskb_expand_head+0x458/0x1390 net/core/skbuff.c:2335 skb_header_unclone include/linux/skbuff.h:2087 [inline] iptunnel_handle_offloads+0x362/0x630 net/ipv4/ip_tunnel_core.c:185 ipip6_tunnel_xmit net/ipv6/sit.c:960 [inline] sit_tunnel_xmit+0x92a/0x1b80 net/ipv6/sit.c:1072 __netdev_start_xmit include/linux/netdevice.h:5368 [inline] netdev_start_xmit include/linux/netdevice.h:5377 [inline] xmit_one net/core/dev.c:3888 [inline] dev_hard_start_xmit+0x2cd/0x830 net/core/dev.c:3904 __dev_queue_xmit+0x14d9/0x3950 net/core/dev.c:4870 packet_snd net/packet/af_packet.c:3082 [inline] packet_sendmsg+0x3c81/0x4fb0 net/packet/af_packet.c:3114 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] __sys_sendto+0x672/0x710 net/socket.c:2265 __do_sys_sendto net/socket.c:2272 [inline] __se_sys_sendto net/socket.c:2268 [inline] __x64_sys_sendto+0xde/0x100 net/socket.c:2268 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff88801bba96c0 which belongs to the cache skbuff_small_head of size 704 The buggy address is located 160 bytes inside of freed 704-byte region [ffff88801bba96c0, ffff88801bba9980) The buggy address belongs to the physical page: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1bba8 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff) page_type: f5(slab) raw: 00fff00000000040 ffff88801f2ad8c0 dead000000000100 dead000000000122 raw: 0000000000000000 0000000800130013 00000000f5000000 0000000000000000 head: 00fff00000000040 ffff88801f2ad8c0 dead000000000100 dead000000000122 head: 0000000000000000 0000000800130013 00000000f5000000 0000000000000000 head: 00fff00000000002 ffffffffffffff01 00000000ffffffff 00000000ffffffff head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5003, tgid 5003 (udevd), ts 31613474311, free_ts 31513004909 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x22d/0x280 mm/page_alloc.c:1853 prep_new_page mm/page_alloc.c:1861 [inline] get_page_from_freelist+0x2593/0x2610 mm/page_alloc.c:3941 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5221 alloc_slab_page mm/slub.c:3278 [inline] allocate_slab+0x77/0x660 mm/slub.c:3467 new_slab mm/slub.c:3525 [inline] refill_objects+0x339/0x3d0 mm/slub.c:7272 refill_sheaf mm/slub.c:2816 [inline] __pcs_replace_empty_main+0x321/0x720 mm/slub.c:4652 alloc_from_pcs mm/slub.c:4750 [inline] slab_alloc_node mm/slub.c:4884 [inline] kmem_cache_alloc_node_noprof+0x441/0x690 mm/slub.c:4951 kmalloc_reserve net/core/skbuff.c:613 [inline] __alloc_skb+0x27d/0x7d0 net/core/skbuff.c:713 netlink_sendmsg+0x5d4/0xb40 net/netlink/af_netlink.c:1874 sock_sendmsg_nosec net/socket.c:787 [inline] __sock_sendmsg net/socket.c:802 [inline] ____sys_sendmsg+0x972/0x9f0 net/socket.c:2698 ___sys_sendmsg+0x2a5/0x360 net/socket.c:2752 __sys_sendmsg net/socket.c:2784 [inline] __do_sys_sendmsg net/socket.c:2789 [inline] __se_sys_sendmsg net/socket.c:2787 [inline] __x64_sys_sendmsg+0x1bd/0x2a0 net/socket.c:2787 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f page last free pid 5001 tgid 5001 stack trace: reset_page_owner include/linux/page_owner.h:25 [inline] __free_pages_prepare mm/page_alloc.c:1397 [inline] __free_frozen_pages+0xc1c/0xd30 mm/page_alloc.c:2938 __slab_free+0x274/0x2c0 mm/slub.c:5613 qlink_free mm/kasan/quarantine.c:163 [inline] qlist_free_all+0x99/0x100 mm/kasan/quarantine.c:179 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:350 kasan_slab_alloc include/linux/kasan.h:253 [inline] slab_post_alloc_hook mm/slub.c:4570 [inline] slab_alloc_node mm/slub.c:4899 [inline] kmem_cache_alloc_noprof+0x2bc/0x650 mm/slub.c:4906 lsm_file_alloc security/security.c:171 [inline] security_file_alloc+0x34/0x310 security/security.c:2406 init_file+0x90/0x2b0 fs/file_table.c:184 alloc_empty_file+0x74/0x1d0 fs/file_table.c:266 path_openat+0x10f/0x3860 fs/namei.c:4844 do_file_open+0x23e/0x4a0 fs/namei.c:4887 do_sys_openat2+0x113/0x200 fs/open.c:1364 do_sys_open fs/open.c:1370 [inline] __do_sys_openat fs/open.c:1386 [inline] __se_sys_openat fs/open.c:1381 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1381 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Memory state around the buggy address: ffff88801bba9600: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff88801bba9680: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb >ffff88801bba9700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88801bba9780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88801bba9800: 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
2026/06/06 09:15	net	c93952cc0034	cc095639	.config	console log	report			info	[disk image] [vmlinux] [kernel image]	ci-upstream-net-this-kasan-gce	KASAN: slab-use-after-free Read in sit_tunnel_xmit

Crashes (1):

Assets (help?)