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BUG: KASAN: use-after-free in memcpy include/linux/string.h:344 [inline]
BUG: KASAN: use-after-free in map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584
Read of size 4 at addr ffff8801c1464dd8 by task syz-executor5/22720

CPU: 1 PID: 22720 Comm: syz-executor5 Not tainted 4.15.0-rc7-next-20180111+ #94
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:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report+0x23b/0x360 mm/kasan/report.c:412
 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]
 map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584
 SYSC_bpf kernel/bpf/syscall.c:1808 [inline]
 SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1782
 entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x452ac9
RSP: 002b:00007f9caba27c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000000000018 RSI: 0000000020c3c000 RDI: 0000000000000001
RBP: 0000000000000403 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f40e8
R13: 00000000ffffffff R14: 00007f9caba286d4 R15: 0000000000000000

Allocated by task 19155:
 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:552
 __do_kmalloc mm/slab.c:3705 [inline]
 __kmalloc+0x162/0x760 mm/slab.c:3714
 kmalloc_array include/linux/slab.h:634 [inline]
 kcalloc include/linux/slab.h:645 [inline]
 iter_file_splice_write+0x247/0xf30 fs/splice.c:692
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x125/0x180 fs/splice.c:1018
 splice_direct_to_actor+0x2c1/0x820 fs/splice.c:973
 do_splice_direct+0x29b/0x3c0 fs/splice.c:1061
 do_sendfile+0x5c9/0xe80 fs/read_write.c:1413
 SYSC_sendfile64 fs/read_write.c:1468 [inline]
 SyS_sendfile64+0xbd/0x160 fs/read_write.c:1460
 entry_SYSCALL_64_fastpath+0x29/0xa0

Freed by task 19155:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:520
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:527
 __cache_free mm/slab.c:3485 [inline]
 kfree+0xd9/0x260 mm/slab.c:3800
 iter_file_splice_write+0x6af/0xf30 fs/splice.c:776
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x125/0x180 fs/splice.c:1018
 splice_direct_to_actor+0x2c1/0x820 fs/splice.c:973
 do_splice_direct+0x29b/0x3c0 fs/splice.c:1061
 do_sendfile+0x5c9/0xe80 fs/read_write.c:1413
 SYSC_sendfile64 fs/read_write.c:1468 [inline]
 SyS_sendfile64+0xbd/0x160 fs/read_write.c:1460
 entry_SYSCALL_64_fastpath+0x29/0xa0

The buggy address belongs to the object at ffff8801c1464d40
 which belongs to the cache kmalloc-256 of size 256
The buggy address is located 152 bytes inside of
 256-byte region [ffff8801c1464d40, ffff8801c1464e40)
The buggy address belongs to the page:
page:ffffea0007051900 count:1 mapcount:0 mapping:ffff8801c14640c0 index:0xffff8801c1464ac0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801c14640c0 ffff8801c1464ac0 0000000100000002
raw: ffffea00076193a0 ffffea0006f717e0 ffff8801dac007c0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c1464c80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c1464d00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8801c1464d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8801c1464e00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8801c1464e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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