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BUG: KASAN: use-after-free in erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735
Read of size 2 at addr ffff8801ce48e7cb by task syz-executor1/25288

CPU: 0 PID: 25288 Comm: syz-executor1 Not tainted 4.15.0-rc8+ #205
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+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440
 erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735
 __netdev_start_xmit include/linux/netdevice.h:4055 [inline]
 netdev_start_xmit include/linux/netdevice.h:4064 [inline]
 packet_direct_xmit+0x3ad/0x790 net/packet/af_packet.c:267
 packet_snd net/packet/af_packet.c:2944 [inline]
 packet_sendmsg+0x3aed/0x60b0 net/packet/af_packet.c:2969
 sock_sendmsg_nosec net/socket.c:630 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:640
 SYSC_sendto+0x361/0x5c0 net/socket.c:1721
Dead loop on virtual device ip6_vti0, fix it urgently!
Dead loop on virtual device ip6_vti0, fix it urgently!
 SyS_sendto+0x40/0x50 net/socket.c:1689
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007ff287f7ac58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000071bf58 RCX: 0000000000452f19
RDX: 0000000000000000 RSI: 0000000020015f41 RDI: 0000000000000016
RBP: 00000000000000b7 R08: 0000000020015fec R09: 0000000000000014
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f01c8
R13: 00000000ffffffff R14: 00007ff287f7b6d4 R15: 0000000000000006

Allocated by task 24120:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489
 kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544
 kmem_cache_zalloc include/linux/slab.h:678 [inline]
 file_alloc_security security/selinux/hooks.c:369 [inline]
 selinux_file_alloc_security+0xae/0x190 security/selinux/hooks.c:3454
 security_file_alloc+0x6d/0xa0 security/security.c:873
 get_empty_filp+0x189/0x4f0 fs/file_table.c:129
 alloc_file+0x26/0x390 fs/file_table.c:164
 sock_alloc_file+0x1f3/0x560 net/socket.c:411
 sock_map_fd+0x34/0x90 net/socket.c:438
 SYSC_socket net/socket.c:1333 [inline]
 SyS_socket+0x125/0x1d0 net/socket.c:1309
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 24132:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3488 [inline]
 kmem_cache_free+0x83/0x2a0 mm/slab.c:3746
 file_free_security security/selinux/hooks.c:384 [inline]
 selinux_file_free_security+0x49/0x60 security/selinux/hooks.c:3459
 security_file_free+0x48/0x80 security/security.c:878
 __fput+0x334/0x7e0 fs/file_table.c:211
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 exit_task_work include/linux/task_work.h:22 [inline]
 do_exit+0x9bb/0x1ad0 kernel/exit.c:865
 do_group_exit+0x149/0x400 kernel/exit.c:968
 get_signal+0x73f/0x16c0 kernel/signal.c:2335
 do_signal+0x90/0x1eb0 arch/x86/kernel/signal.c:809
 exit_to_usermode_loop+0x214/0x310 arch/x86/entry/common.c:158
 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline]
 syscall_return_slowpath+0x490/0x550 arch/x86/entry/common.c:264
 entry_SYSCALL_64_fastpath+0x9e/0xa0

The buggy address belongs to the object at ffff8801ce48e7c0
 which belongs to the cache selinux_file_security of size 16
The buggy address is located 11 bytes inside of
 16-byte region [ffff8801ce48e7c0, ffff8801ce48e7d0)
The buggy address belongs to the page:
page:ffffea0007392380 count:1 mapcount:0 mapping:ffff8801ce48e000 index:0xffff8801ce48ef84
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801ce48e000 ffff8801ce48ef84 000000010000007c
raw: ffffea0006f5b0a0 ffffea00073c8f20 ffff8801dae270c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801ce48e680: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
 ffff8801ce48e700: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
>ffff8801ce48e780: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
                                              ^
 ffff8801ce48e800: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
 ffff8801ce48e880: fb fb fc fc fb fb fc fc fb fb fc fc fb fb fc fc
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