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BUG: KASAN: use-after-free in _copy_to_user+0x9a/0xc0 lib/usercopy.c:27
Read of size 1134 at addr ffff8801893ffffc by task syz-executor3/24456

CPU: 1 PID: 24456 Comm: syz-executor3 Not tainted 4.14.81+ #6
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0xb9/0x11b lib/dump_stack.c:53
 print_address_description+0x60/0x22b mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report.cold.6+0x11b/0x2dd mm/kasan/report.c:409
 _copy_to_user+0x9a/0xc0 lib/usercopy.c:27
 copy_to_user include/linux/uaccess.h:155 [inline]
 bpf_test_finish.isra.0+0xc8/0x190 net/bpf/test_run.c:59
 bpf_prog_test_run_skb+0x4d0/0x8c0 net/bpf/test_run.c:144
 bpf_prog_test_run kernel/bpf/syscall.c:1343 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1615 [inline]
 SyS_bpf+0x79d/0x3700 kernel/bpf/syscall.c:1560
 do_syscall_64+0x19b/0x4b0 arch/x86/entry/common.c:289
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x457569
RSP: 002b:00007f701508bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000000000098 RSI: 00000000200002c0 RDI: 000000000000000a
RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f701508c6d4
R13: 00000000004bd892 R14: 00000000004cc568 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea000624ffc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
raw: 4000000000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea000624ffe0 ffffea000624ffe0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801893ffe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8801893fff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8801893fff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff880189400000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff880189400080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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