================================================================== BUG: KASAN: use-after-free in ipv6_get_dsfield include/net/dsfield.h:23 [inline] BUG: KASAN: use-after-free in ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1371 [inline] BUG: KASAN: use-after-free in ip6_tnl_start_xmit+0x173b/0x1870 net/ipv6/ip6_tunnel.c:1398 Read of size 2 at addr ffff8800b8e0db90 by task syz-executor.3/5901 CPU: 1 PID: 5901 Comm: syz-executor.3 Not tainted 4.9.141+ #1 ffff8800b967efd8 ffffffff81b42e79 ffffea0002e38300 ffff8800b8e0db90 0000000000000000 ffff8800b8e0db90 ffff8800b8e0db90 ffff8800b967f010 ffffffff815009b8 ffff8800b8e0db90 0000000000000002 0000000000000000 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] print_address_description+0x6c/0x234 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report.cold.6+0x242/0x2fe mm/kasan/report.c:412 [] __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431 [] ipv6_get_dsfield include/net/dsfield.h:23 [inline] [] ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1371 [inline] [] ip6_tnl_start_xmit+0x173b/0x1870 net/ipv6/ip6_tunnel.c:1398 [] __netdev_start_xmit include/linux/netdevice.h:4069 [inline] [] netdev_start_xmit include/linux/netdevice.h:4078 [inline] [] xmit_one net/core/dev.c:2977 [inline] [] dev_hard_start_xmit+0x197/0x8b0 net/core/dev.c:2993 [] __dev_queue_xmit+0x117f/0x1b90 net/core/dev.c:3473 [] dev_queue_xmit+0x17/0x20 net/core/dev.c:3506 [] neigh_direct_output+0x15/0x20 net/core/neighbour.c:1365 [] dst_neigh_output include/net/dst.h:470 [inline] [] ip6_finish_output2+0xb0e/0x1d10 net/ipv6/ip6_output.c:119 [] ip6_finish_output+0x334/0x980 net/ipv6/ip6_output.c:145 [] NF_HOOK_COND include/linux/netfilter.h:246 [inline] [] ip6_output+0x1ea/0x6d0 net/ipv6/ip6_output.c:162 [] dst_output include/net/dst.h:507 [inline] [] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:176 [] ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1751 [] udp_v6_send_skb+0x843/0xe70 net/ipv6/udp.c:974 [] udpv6_sendmsg+0x1ebb/0x2430 net/ipv6/udp.c:1246 [] inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770 [] sock_sendmsg_nosec net/socket.c:648 [inline] [] sock_sendmsg+0xbb/0x110 net/socket.c:658 [] ___sys_sendmsg+0x47a/0x840 net/socket.c:1982 [] __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072 [] SYSC_sendmmsg net/socket.c:2103 [inline] [] SyS_sendmmsg+0x35/0x60 net/socket.c:2098 [] do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 5901: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:609 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:594 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:547 slab_post_alloc_hook mm/slab.h:417 [inline] slab_alloc_node mm/slub.c:2715 [inline] slab_alloc mm/slub.c:2723 [inline] __kmalloc_track_caller+0xf0/0x2d0 mm/slub.c:4232 __kmalloc_reserve.isra.5+0x33/0xc0 net/core/skbuff.c:138 __alloc_skb+0x11a/0x5b0 net/core/skbuff.c:231 alloc_skb include/linux/skbuff.h:924 [inline] alloc_skb_with_frags+0xaf/0x4e0 net/core/skbuff.c:4707 sock_alloc_send_pskb+0x59e/0x740 net/core/sock.c:1893 sock_alloc_send_skb+0x32/0x40 net/core/sock.c:1910 ip6_ufo_append_data net/ipv6/ip6_output.c:1145 [inline] __ip6_append_data.isra.3+0x1a29/0x3460 net/ipv6/ip6_output.c:1408 ip6_make_skb+0x291/0x480 net/ipv6/ip6_output.c:1831 udpv6_sendmsg+0x1e89/0x2430 net/ipv6/udp.c:1240 inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770 sock_sendmsg_nosec net/socket.c:648 [inline] sock_sendmsg+0xbb/0x110 net/socket.c:658 ___sys_sendmsg+0x47a/0x840 net/socket.c:1982 __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072 SYSC_sendmmsg net/socket.c:2103 [inline] SyS_sendmmsg+0x35/0x60 net/socket.c:2098 do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 5901: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:57 save_stack mm/kasan/kasan.c:505 [inline] set_track mm/kasan/kasan.c:517 [inline] kasan_slab_free+0xac/0x190 mm/kasan/kasan.c:582 slab_free_hook mm/slub.c:1355 [inline] slab_free_freelist_hook mm/slub.c:1377 [inline] slab_free mm/slub.c:2958 [inline] kfree+0xfb/0x310 mm/slub.c:3878 skb_free_head+0x8b/0xb0 net/core/skbuff.c:580 pskb_expand_head+0x457/0x8a0 net/core/skbuff.c:1246 skb_header_unclone include/linux/skbuff.h:1364 [inline] iptunnel_handle_offloads+0x3f0/0x520 net/ipv4/ip_tunnel_core.c:169 ip6ip6_tnl_xmit net/ipv6/ip6_tunnel.c:1368 [inline] ip6_tnl_start_xmit+0x568/0x1870 net/ipv6/ip6_tunnel.c:1398 __netdev_start_xmit include/linux/netdevice.h:4069 [inline] netdev_start_xmit include/linux/netdevice.h:4078 [inline] xmit_one net/core/dev.c:2977 [inline] dev_hard_start_xmit+0x197/0x8b0 net/core/dev.c:2993 __dev_queue_xmit+0x117f/0x1b90 net/core/dev.c:3473 dev_queue_xmit+0x17/0x20 net/core/dev.c:3506 neigh_direct_output+0x15/0x20 net/core/neighbour.c:1365 dst_neigh_output include/net/dst.h:470 [inline] ip6_finish_output2+0xb0e/0x1d10 net/ipv6/ip6_output.c:119 ip6_finish_output+0x334/0x980 net/ipv6/ip6_output.c:145 NF_HOOK_COND include/linux/netfilter.h:246 [inline] ip6_output+0x1ea/0x6d0 net/ipv6/ip6_output.c:162 dst_output include/net/dst.h:507 [inline] ip6_local_out+0x9b/0x180 net/ipv6/output_core.c:176 ip6_send_skb+0xa1/0x340 net/ipv6/ip6_output.c:1751 udp_v6_send_skb+0x843/0xe70 net/ipv6/udp.c:974 udpv6_sendmsg+0x1ebb/0x2430 net/ipv6/udp.c:1246 inet_sendmsg+0x203/0x4d0 net/ipv4/af_inet.c:770 sock_sendmsg_nosec net/socket.c:648 [inline] sock_sendmsg+0xbb/0x110 net/socket.c:658 ___sys_sendmsg+0x47a/0x840 net/socket.c:1982 __sys_sendmmsg+0x161/0x3d0 net/socket.c:2072 SYSC_sendmmsg net/socket.c:2103 [inline] SyS_sendmmsg+0x35/0x60 net/socket.c:2098 do_syscall_64+0x19f/0x550 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb The buggy address belongs to the object at ffff8800b8e0db00 which belongs to the cache kmalloc-1024 of size 1024 The buggy address is located 144 bytes inside of 1024-byte region [ffff8800b8e0db00, ffff8800b8e0df00) The buggy address belongs to the page: page:ffffea0002e38300 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x4080(slab|head) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8800b8e0da80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8800b8e0db00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8800b8e0db80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8800b8e0dc00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8800b8e0dc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================