protocol 0800 is buggy, dev ip6tnl0 ================================================================== BUG: KASAN: use-after-free in atomic_sub_return include/asm-generic/atomic-instrumented.h:258 [inline] BUG: KASAN: use-after-free in skb_release_data+0x19b/0x860 net/core/skbuff.c:559 Write of size 4 at addr ffff8801d43d4860 by task syz-executor3/19252 CPU: 1 PID: 19252 Comm: syz-executor3 Not tainted 4.17.0-rc5+ #56 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x1b9/0x294 lib/dump_stack.c:113 print_address_description+0x6c/0x20b mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412 check_memory_region_inline mm/kasan/kasan.c:260 [inline] check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267 kasan_check_write+0x14/0x20 mm/kasan/kasan.c:278 atomic_sub_return include/asm-generic/atomic-instrumented.h:258 [inline] skb_release_data+0x19b/0x860 net/core/skbuff.c:559 skb_release_all+0x4a/0x60 net/core/skbuff.c:627 __kfree_skb net/core/skbuff.c:641 [inline] kfree_skb+0x195/0x560 net/core/skbuff.c:659 skb_queue_purge+0x19/0x40 net/core/skbuff.c:2838 packet_release+0x9d1/0xd60 net/packet/af_packet.c:3047 sock_release+0x96/0x1b0 net/socket.c:594 sock_close+0x16/0x20 net/socket.c:1149 __fput+0x34d/0x890 fs/file_table.c:209 ____fput+0x15/0x20 fs/file_table.c:243 task_work_run+0x1e4/0x290 kernel/task_work.c:113 exit_task_work include/linux/task_work.h:22 [inline] do_exit+0x1aee/0x2730 kernel/exit.c:865 do_group_exit+0x16f/0x430 kernel/exit.c:968 get_signal+0x886/0x1960 kernel/signal.c:2482 do_signal+0x98/0x2040 arch/x86/kernel/signal.c:810 exit_to_usermode_loop+0x28a/0x310 arch/x86/entry/common.c:162 prepare_exit_to_usermode arch/x86/entry/common.c:196 [inline] syscall_return_slowpath arch/x86/entry/common.c:265 [inline] do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x455a09 RSP: 002b:00007f54cbe03ce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca RAX: fffffffffffffe00 RBX: 000000000072bf78 RCX: 0000000000455a09 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000072bf78 RBP: 000000000072bf78 R08: 0000000000000000 R09: 000000000072bf50 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fffddd4f33f R14: 00007f54cbe049c0 R15: 0000000000000001 Allocated by task 19252: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553 __do_kmalloc_node mm/slab.c:3682 [inline] __kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3696 __kmalloc_reserve.isra.38+0x3a/0xe0 net/core/skbuff.c:137 __alloc_skb+0x14d/0x780 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:987 [inline] alloc_skb_with_frags+0x137/0x760 net/core/skbuff.c:5249 sock_alloc_send_pskb+0x87a/0xae0 net/core/sock.c:2088 packet_alloc_skb net/packet/af_packet.c:2810 [inline] packet_snd net/packet/af_packet.c:2901 [inline] packet_sendmsg+0x1b98/0x6070 net/packet/af_packet.c:2976 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 __sys_sendto+0x3d7/0x670 net/socket.c:1789 __do_sys_sendto net/socket.c:1801 [inline] __se_sys_sendto net/socket.c:1797 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 19252: save_stack+0x43/0xd0 mm/kasan/kasan.c:448 set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3498 [inline] kfree+0xd9/0x260 mm/slab.c:3813 skb_free_head+0x99/0xc0 net/core/skbuff.c:550 skb_release_data+0x690/0x860 net/core/skbuff.c:570 skb_release_all+0x4a/0x60 net/core/skbuff.c:627 __kfree_skb net/core/skbuff.c:641 [inline] kfree_skb+0x195/0x560 net/core/skbuff.c:659 ip6_tnl_start_xmit+0xa44/0x2290 net/ipv6/ip6_tunnel.c:1411 __netdev_start_xmit include/linux/netdevice.h:4087 [inline] netdev_start_xmit include/linux/netdevice.h:4096 [inline] xmit_one net/core/dev.c:3053 [inline] dev_hard_start_xmit+0x264/0xc10 net/core/dev.c:3069 __dev_queue_xmit+0x2724/0x34c0 net/core/dev.c:3584 dev_queue_xmit+0x17/0x20 net/core/dev.c:3617 packet_snd net/packet/af_packet.c:2951 [inline] packet_sendmsg+0x40f8/0x6070 net/packet/af_packet.c:2976 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xd5/0x120 net/socket.c:639 __sys_sendto+0x3d7/0x670 net/socket.c:1789 __do_sys_sendto net/socket.c:1801 [inline] __se_sys_sendto net/socket.c:1797 [inline] __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1797 do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff8801d43d4780 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 224 bytes inside of 512-byte region [ffff8801d43d4780, ffff8801d43d4980) The buggy address belongs to the page: page:ffffea000750f500 count:1 mapcount:0 mapping:ffff8801d43d4000 index:0xffff8801d43d4c80 flags: 0x2fffc0000000100(slab) raw: 02fffc0000000100 ffff8801d43d4000 ffff8801d43d4c80 0000000100000005 raw: ffffea0006dda1a0 ffffea00075a30a0 ffff8801da800940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8801d43d4700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801d43d4780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff8801d43d4800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8801d43d4880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8801d43d4900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================