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BUG: KASAN: slab-out-of-bounds in erspan_xmit+0x22d4/0x2430 net/ipv4/ip_gre.c:735
Read of size 2 at addr ffff8801d0cf104b by task syz-executor2/27078

CPU: 0 PID: 27078 Comm: syz-executor2 Not tainted 4.15.0-rc9+ #206
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:00007f7ff0f0dc58 EFLAGS: 00000212 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452f19
RDX: 0000000000000000 RSI: 0000000020014000 RDI: 0000000000000013
RBP: 00000000000003d6 R08: 0000000020008000 R09: 000000000000001c
R10: 0000000000008010 R11: 0000000000000212 R12: 00000000006f4cb0
R13: 00000000ffffffff R14: 00007f7ff0f0e6d4 R15: 0000000000000000

Allocated by task 5969:
 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
 __do_kmalloc mm/slab.c:3708 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3717
 kmalloc include/linux/slab.h:504 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 new_dir fs/proc/proc_sysctl.c:939 [inline]
 get_subdir fs/proc/proc_sysctl.c:984 [inline]
 __register_sysctl_table+0x91d/0x10b0 fs/proc/proc_sysctl.c:1327
 register_net_sysctl+0x29/0x30 net/sysctl_net.c:120
 __addrconf_sysctl_register+0x21a/0x400 net/ipv6/addrconf.c:6403
 addrconf_sysctl_register+0x116/0x1b0 net/ipv6/addrconf.c:6450
 ipv6_add_dev+0xa3d/0x1310 net/ipv6/addrconf.c:458
 addrconf_notify+0x86e/0x2310 net/ipv6/addrconf.c:3380
 notifier_call_chain+0x136/0x2c0 kernel/notifier.c:93
 __raw_notifier_call_chain kernel/notifier.c:394 [inline]
 raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
 call_netdevice_notifiers_info+0x32/0x70 net/core/dev.c:1707
 call_netdevice_notifiers net/core/dev.c:1725 [inline]
 register_netdevice+0xd40/0x1020 net/core/dev.c:7881
 register_netdev+0x1a/0x30 net/core/dev.c:7966
 br_add_bridge+0x97/0xd0 net/bridge/br_if.c:394
 old_deviceless net/bridge/br_ioctl.c:349 [inline]
 br_ioctl_deviceless_stub+0x8fe/0xa00 net/bridge/br_ioctl.c:363
 sock_ioctl+0x383/0x440 net/socket.c:1022
 vfs_ioctl fs/ioctl.c:46 [inline]
 do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 1211:
 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
 skb_free_head+0x74/0xb0 net/core/skbuff.c:550
 skb_release_data+0x58c/0x790 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+0x15d/0x4c0 net/core/skbuff.c:659
 unix_release_sock+0x5e3/0xc10 net/unix/af_unix.c:560
 unix_release+0x44/0x90 net/unix/af_unix.c:838
 sock_release+0x8d/0x1e0 net/socket.c:595
 sock_close+0x16/0x20 net/socket.c:1123
 __fput+0x327/0x7e0 fs/file_table.c:210
 ____fput+0x15/0x20 fs/file_table.c:244
 task_work_run+0x199/0x270 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x296/0x310 arch/x86/entry/common.c:162
 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 ffff8801d0cf1080
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 53 bytes to the left of
 512-byte region [ffff8801d0cf1080, ffff8801d0cf1280)
The buggy address belongs to the page:
page:ffffea0007433c40 count:1 mapcount:0 mapping:ffff8801d0cf1080 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801d0cf1080 0000000000000000 0000000100000006
raw: ffffea000743b5a0 ffffea00072bb520 ffff8801dac00940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801d0cf0f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801d0cf0f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff8801d0cf1000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff8801d0cf1080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801d0cf1100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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