================================================================== 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:1372 [inline] BUG: KASAN: use-after-free in ip6_tnl_start_xmit+0x16fb/0x18a0 net/ipv6/ip6_tunnel.c:1399 Read of size 2 at addr ffff8801af8b8e18 by task syz-executor.4/30394 CPU: 0 PID: 30394 Comm: syz-executor.4 Not tainted 4.9.155+ #27 ffff8801ab5ff090 ffffffff81b47871 0000000000000000 ffffea0006be2e00 ffff8801af8b8e18 0000000000000002 ffffffff827b086b ffff8801ab5ff0c8 ffffffff81502825 0000000000000000 ffff8801af8b8e18 ffff8801af8b8e18 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [] print_address_description+0x6f/0x238 mm/kasan/report.c:256 [] kasan_report_error mm/kasan/report.c:355 [inline] [] kasan_report mm/kasan/report.c:412 [inline] [] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397 [] __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:1372 [inline] [] ip6_tnl_start_xmit+0x16fb/0x18a0 net/ipv6/ip6_tunnel.c:1399 [] __netdev_start_xmit include/linux/netdevice.h:4072 [inline] [] netdev_start_xmit include/linux/netdevice.h:4081 [inline] [] xmit_one net/core/dev.c:2977 [inline] [] dev_hard_start_xmit+0x195/0x8b0 net/core/dev.c:2993 [] __dev_queue_xmit+0x11a3/0x1bd0 net/core/dev.c:3473 [] dev_queue_xmit+0x18/0x20 net/core/dev.c:3506 [] neigh_direct_output+0x16/0x20 net/core/neighbour.c:1365 [] dst_neigh_output include/net/dst.h:470 [inline] [] ip6_finish_output2+0x94f/0x1e50 net/ipv6/ip6_output.c:119 [] ip6_finish_output+0x336/0x970 net/ipv6/ip6_output.c:145 [] NF_HOOK_COND include/linux/netfilter.h:246 [inline] [] ip6_output+0x21b/0x730 net/ipv6/ip6_output.c:162 [] dst_output include/net/dst.h:507 [inline] [] ip6_local_out+0x9c/0x180 net/ipv6/output_core.c:176 [] ip6_send_skb+0xa2/0x340 net/ipv6/ip6_output.c:1751 [] udp_v6_send_skb+0x85c/0xe90 net/ipv6/udp.c:974 [] udp_v6_push_pending_frames+0x245/0x360 net/ipv6/udp.c:1007 [] udpv6_sendmsg+0x19b0/0x2430 net/ipv6/udp.c:1273 [] inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:770 [] sock_sendmsg_nosec net/socket.c:648 [inline] [] sock_sendmsg+0xbe/0x110 net/socket.c:658 [] sock_write_iter+0x235/0x3d0 net/socket.c:856 [] new_sync_write fs/read_write.c:498 [inline] [] __vfs_write+0x3c1/0x560 fs/read_write.c:511 [] vfs_write+0x185/0x520 fs/read_write.c:559 [] SYSC_write fs/read_write.c:606 [inline] [] SyS_write+0xdc/0x1c0 fs/read_write.c:598 [] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Allocated by task 30394: 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.0+0x62/0xf0 mm/kasan/kasan.c:609 kasan_kmalloc+0xb7/0xd0 mm/kasan/kasan.c:594 kasan_slab_alloc+0xf/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+0xf4/0x2d0 mm/slub.c:4232 __kmalloc_reserve.isra.0+0x33/0xc0 net/core/skbuff.c:138 __alloc_skb+0x11a/0x5e0 net/core/skbuff.c:231 alloc_skb include/linux/skbuff.h:924 [inline] alloc_skb_with_frags+0xb0/0x4f0 net/core/skbuff.c:4711 sock_alloc_send_pskb+0x5ec/0x760 net/core/sock.c:1894 sock_alloc_send_skb+0x32/0x40 net/core/sock.c:1911 __ip6_append_data.isra.0+0x1fc0/0x3440 net/ipv6/ip6_output.c:1485 ip6_append_data+0x1d4/0x300 net/ipv6/ip6_output.c:1645 udpv6_sendmsg+0x86b/0x2430 net/ipv6/udp.c:1267 inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:770 sock_sendmsg_nosec net/socket.c:648 [inline] sock_sendmsg+0xbe/0x110 net/socket.c:658 SYSC_sendto net/socket.c:1683 [inline] SyS_sendto+0x201/0x340 net/socket.c:1651 do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb Freed by task 30394: 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+0xb0/0x190 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+0x44a/0x8b0 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:1369 [inline] ip6_tnl_start_xmit+0x561/0x18a0 net/ipv6/ip6_tunnel.c:1399 __netdev_start_xmit include/linux/netdevice.h:4072 [inline] netdev_start_xmit include/linux/netdevice.h:4081 [inline] xmit_one net/core/dev.c:2977 [inline] dev_hard_start_xmit+0x195/0x8b0 net/core/dev.c:2993 __dev_queue_xmit+0x11a3/0x1bd0 net/core/dev.c:3473 dev_queue_xmit+0x18/0x20 net/core/dev.c:3506 neigh_direct_output+0x16/0x20 net/core/neighbour.c:1365 dst_neigh_output include/net/dst.h:470 [inline] ip6_finish_output2+0x94f/0x1e50 net/ipv6/ip6_output.c:119 ip6_finish_output+0x336/0x970 net/ipv6/ip6_output.c:145 NF_HOOK_COND include/linux/netfilter.h:246 [inline] ip6_output+0x21b/0x730 net/ipv6/ip6_output.c:162 dst_output include/net/dst.h:507 [inline] ip6_local_out+0x9c/0x180 net/ipv6/output_core.c:176 ip6_send_skb+0xa2/0x340 net/ipv6/ip6_output.c:1751 udp_v6_send_skb+0x85c/0xe90 net/ipv6/udp.c:974 udp_v6_push_pending_frames+0x245/0x360 net/ipv6/udp.c:1007 udpv6_sendmsg+0x19b0/0x2430 net/ipv6/udp.c:1273 inet_sendmsg+0x202/0x4d0 net/ipv4/af_inet.c:770 sock_sendmsg_nosec net/socket.c:648 [inline] sock_sendmsg+0xbe/0x110 net/socket.c:658 sock_write_iter+0x235/0x3d0 net/socket.c:856 new_sync_write fs/read_write.c:498 [inline] __vfs_write+0x3c1/0x560 fs/read_write.c:511 vfs_write+0x185/0x520 fs/read_write.c:559 SYSC_write fs/read_write.c:606 [inline] SyS_write+0xdc/0x1c0 fs/read_write.c:598 do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 entry_SYSCALL_64_after_swapgs+0x5d/0xdb The buggy address belongs to the object at ffff8801af8b8d80 which belongs to the cache kmalloc-1024 of size 1024 The buggy address is located 152 bytes inside of 1024-byte region [ffff8801af8b8d80, ffff8801af8b9180) The buggy address belongs to the page: page:ffffea0006be2e00 count:1 mapcount:0 mapping: (null) index:0x0 compound_mapcount: 0 flags: 0x4000000000004080(slab|head) page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801af8b8d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801af8b8d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801af8b8e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801af8b8e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801af8b8f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================