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BUG: KASAN: use-after-free in ip_tunnel_xmit+0x246f/0x3390 net/ipv4/ip_tunnel.c:659
Read of size 4 at addr ffff888099324b70 by task syz-executor.5/9622

CPU: 1 PID: 9622 Comm: syz-executor.5 Not tainted 4.14.222-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x281 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load4_noabort+0x68/0x70 mm/kasan/report.c:429
 ip_tunnel_xmit+0x246f/0x3390 net/ipv4/ip_tunnel.c:659
 ipgre_xmit+0x398/0x6d0 net/ipv4/ip_gre.c:670
 __netdev_start_xmit include/linux/netdevice.h:4041 [inline]
 netdev_start_xmit include/linux/netdevice.h:4050 [inline]
 xmit_one net/core/dev.c:3005 [inline]
 dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021
 __dev_queue_xmit+0x1d7f/0x2480 net/core/dev.c:3521
 packet_snd+0x1393/0x21e0 net/packet/af_packet.c:3024
 packet_sendmsg+0x1139/0x2ad0 net/packet/af_packet.c:3049
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595
 kernel_sendpage net/socket.c:3407 [inline]
 sock_sendpage+0xdf/0x140 net/socket.c:871
 pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0xc1/0x110 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 do_splice fs/splice.c:1147 [inline]
 SYSC_splice fs/splice.c:1402 [inline]
 SyS_splice+0xd59/0x1380 fs/splice.c:1382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x465ef9
RSP: 002b:00007fc79eb18188 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 000000000056c008 RCX: 0000000000465ef9
RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00000000004bcd1c R08: 00000000ffffffff R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c008
R13: 00007ffe8f2197af R14: 00007fc79eb18300 R15: 0000000000022000

Allocated by task 9622:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node_track_caller+0x4c/0x70 mm/slab.c:3696
 __kmalloc_reserve net/core/skbuff.c:137 [inline]
 __alloc_skb+0x96/0x510 net/core/skbuff.c:205
 skb_segment+0x677/0x2e60 net/core/skbuff.c:3668
 udp4_ufo_fragment+0x40b/0x690 net/ipv4/udp_offload.c:242
 inet_gso_segment+0x470/0x10c0 net/ipv4/af_inet.c:1272
 skb_mac_gso_segment+0x240/0x4c0 net/core/dev.c:2745
 __skb_gso_segment+0x302/0x600 net/core/dev.c:2818
 skb_gso_segment include/linux/netdevice.h:3992 [inline]
 validate_xmit_skb+0x49c/0x9f0 net/core/dev.c:3071
 __dev_queue_xmit+0x816/0x2480 net/core/dev.c:3513
 packet_snd+0x1393/0x21e0 net/packet/af_packet.c:3024
 packet_sendmsg+0x1139/0x2ad0 net/packet/af_packet.c:3049
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595
 kernel_sendpage net/socket.c:3407 [inline]
 sock_sendpage+0xdf/0x140 net/socket.c:871
 pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0xc1/0x110 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 do_splice fs/splice.c:1147 [inline]
 SYSC_splice fs/splice.c:1402 [inline]
 SyS_splice+0xd59/0x1380 fs/splice.c:1382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 9622:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 skb_free_head net/core/skbuff.c:563 [inline]
 pskb_expand_head+0x895/0xd30 net/core/skbuff.c:1504
 __pskb_pull_tail+0xd9/0x14a0 net/core/skbuff.c:1907
 pskb_may_pull include/linux/skbuff.h:2180 [inline]
 ip_tunnel_xmit+0x142c/0x3390 net/ipv4/ip_tunnel.c:651
 ipgre_xmit+0x398/0x6d0 net/ipv4/ip_gre.c:670
 __netdev_start_xmit include/linux/netdevice.h:4041 [inline]
 netdev_start_xmit include/linux/netdevice.h:4050 [inline]
 xmit_one net/core/dev.c:3005 [inline]
 dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021
 __dev_queue_xmit+0x1d7f/0x2480 net/core/dev.c:3521
 packet_snd+0x1393/0x21e0 net/packet/af_packet.c:3024
 packet_sendmsg+0x1139/0x2ad0 net/packet/af_packet.c:3049
 sock_sendmsg_nosec net/socket.c:646 [inline]
 sock_sendmsg+0xb5/0x100 net/socket.c:656
 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595
 kernel_sendpage net/socket.c:3407 [inline]
 sock_sendpage+0xdf/0x140 net/socket.c:871
 pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 generic_splice_sendpage+0xc1/0x110 fs/splice.c:832
 do_splice_from fs/splice.c:851 [inline]
 do_splice fs/splice.c:1147 [inline]
 SYSC_splice fs/splice.c:1402 [inline]
 SyS_splice+0xd59/0x1380 fs/splice.c:1382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff888099324ac0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 176 bytes inside of
 512-byte region [ffff888099324ac0, ffff888099324cc0)
The buggy address belongs to the page:
page:ffffea000264c900 count:1 mapcount:0 mapping:ffff8880993240c0 index:0x0
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880993240c0 0000000000000000 0000000100000006
raw: ffffea000262f5e0 ffffea000264d1e0 ffff88813fe80940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888099324a00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff888099324a80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff888099324b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                             ^
 ffff888099324b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888099324c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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