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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 ffff8801c8b63d0b by task syz-executor2/21978

CPU: 1 PID: 21978 Comm: syz-executor2 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:00007fe8320bcc58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452f19
RDX: 0000000000000000 RSI: 0000000020003fd9 RDI: 0000000000000013
RBP: 000000000000059c R08: 0000000020008000 R09: 000000000000001c
R10: fffffffffffffffe R11: 0000000000000212 R12: 00000000006f7740
R13: 00000000ffffffff R14: 00007fe8320bd6d4 R15: 0000000000000000

Allocated by task 18076:
 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
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610
 kmalloc include/linux/slab.h:499 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 sctp_add_bind_addr+0xd8/0x460 net/sctp/bind_addr.c:159
 sctp_copy_local_addr_list+0x4bb/0x5e0 net/sctp/protocol.c:230
 sctp_copy_one_addr+0xdc/0x120 net/sctp/bind_addr.c:449
 sctp_bind_addr_copy+0x167/0x360 net/sctp/bind_addr.c:71
 sctp_assoc_set_bind_addr_from_ep+0x136/0x190 net/sctp/associola.c:1578
 sctp_sendmsg+0x1d98/0x35e0 net/sctp/socket.c:1890
 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:764
 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

Freed by task 18078:
 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]
 kfree+0xd6/0x260 mm/slab.c:3803
 __rcu_reclaim kernel/rcu/rcu.h:190 [inline]
 rcu_do_batch kernel/rcu/tree.c:2758 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:3012 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2979 [inline]
 rcu_process_callbacks+0xe94/0x17f0 kernel/rcu/tree.c:2996
 __do_softirq+0x2d7/0xb85 kernel/softirq.c:285

The buggy address belongs to the object at ffff8801c8b63d00
 which belongs to the cache kmalloc-64 of size 64
The buggy address is located 11 bytes inside of
 64-byte region [ffff8801c8b63d00, ffff8801c8b63d40)
The buggy address belongs to the page:
page:ffffea000722d8c0 count:1 mapcount:0 mapping:ffff8801c8b63000 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c8b63000 0000000000000000 0000000100000020
raw: ffffea000718f160 ffff8801dac01348 ffff8801dac00340 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c8b63c00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c8b63c80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff8801c8b63d00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
                      ^
 ffff8801c8b63d80: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c8b63e00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
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