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BUG: KASAN: stack-out-of-bounds in memcpy include/linux/string.h:344 [inline]
BUG: KASAN: stack-out-of-bounds in __nla_put+0x37/0x40 lib/nlattr.c:569
Read of size 255 at addr ffff8801bc7377d0 by task syz-executor2/20941

CPU: 1 PID: 20941 Comm: syz-executor2 Not tainted 4.15.0-rc8+ #175
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
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x137/0x190 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:344 [inline]
 __nla_put+0x37/0x40 lib/nlattr.c:569
 nla_put+0xf5/0x130 lib/nlattr.c:627
 netlink_ack+0x78a/0xa10 net/netlink/af_netlink.c:2371
 netlink_rcv_skb+0x2d1/0x400 net/netlink/af_netlink.c:2415
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:4423
 netlink_unicast_kernel net/netlink/af_netlink.c:1275 [inline]
 netlink_unicast+0x4ee/0x700 net/netlink/af_netlink.c:1301
 netlink_sendmsg+0xa4a/0xe60 net/netlink/af_netlink.c:1864
 sock_sendmsg_nosec net/socket.c:638 [inline]
 sock_sendmsg+0xca/0x110 net/socket.c:648
 sock_write_iter+0x31a/0x5d0 net/socket.c:917
 call_write_iter include/linux/fs.h:1772 [inline]
 new_sync_write fs/read_write.c:469 [inline]
 __vfs_write+0x684/0x970 fs/read_write.c:482
 vfs_write+0x189/0x510 fs/read_write.c:544
 SYSC_write fs/read_write.c:589 [inline]
 SyS_write+0xef/0x220 fs/read_write.c:581
 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
 do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
 entry_SYSENTER_compat+0x54/0x63 arch/x86/entry/entry_64_compat.S:129
RIP: 0023:0xf7ff7c79
RSP: 002b:00000000f77f308c EFLAGS: 00000296 ORIG_RAX: 0000000000000004
RAX: ffffffffffffffda RBX: 0000000000000013 RCX: 0000000020d1afdd
RDX: 0000000000000022 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

The buggy address belongs to the page:
page:ffffea0006f1cdc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x2fffc0000000000()
raw: 02fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bc737680: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffff8801bc737700: 04 f2 f2 f2 f3 f3 f3 f3 00 00 00 00 00 00 00 00
>ffff8801bc737780: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 00 f2 f2 f2
                                                          ^
 ffff8801bc737800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801bc737880: 00 00 00 00 00 f1 f1 f1 f1 00 f2 f2 f2 f3 f3 f3
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