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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 ffff8801d6271acb by task syz-executor7/14141

CPU: 1 PID: 14141 Comm: syz-executor7 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
 SyS_sendto+0x40/0x50 net/socket.c:1689
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452f19
RSP: 002b:00007f9df34b6c58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f9df34b7700 RCX: 0000000000452f19
RDX: 0000000000000000 RSI: 000000002000f000 RDI: 0000000000000013
RBP: 0000000000000000 R08: 0000000020010fe4 R09: 000000000000001c
R10: 0000000000000041 R11: 0000000000000212 R12: 0000000000000000
R13: 0000000000a2f7cf R14: 00007f9df34b79c0 R15: 0000000000000000

Allocated by task 1:
 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
 mempool_alloc_slab+0x44/0x60 mm/mempool.c:450
 mempool_create_node+0x2e4/0x400 mm/mempool.c:211
 mempool_create+0x37/0x40 mm/mempool.c:179
 mempool_create_slab_pool include/linux/mempool.h:49 [inline]
 nfs_init_writepagecache+0x5f/0x176 fs/nfs/write.c:2088
 init_nfs_fs+0xd1/0x1bd fs/nfs/inode.c:2137
 do_one_initcall+0xad/0x357 init/main.c:832
 do_initcall_level init/main.c:898 [inline]
 do_initcalls init/main.c:906 [inline]
 do_basic_setup init/main.c:924 [inline]
 kernel_init_freeable+0x469/0x521 init/main.c:1072
 kernel_init+0x13/0x180 init/main.c:999
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:541

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801d6271ac0
 which belongs to the cache nfs_write_data of size 944
The buggy address is located 11 bytes inside of
 944-byte region [ffff8801d6271ac0, ffff8801d6271e70)
The buggy address belongs to the page:
page:ffffea0007589c00 count:1 mapcount:0 mapping:ffff8801d6270140 index:0xffff8801d6270140 compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801d6270140 ffff8801d6270140 0000000100000004
raw: ffff8801d60b0138 ffff8801d60b0138 ffff8801d6f820c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d6271980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d6271a00: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
>ffff8801d6271a80: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
                                              ^
 ffff8801d6271b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801d6271b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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