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BUG: KASAN: use-after-free in _copy_to_user+0xa4/0xd0 lib/usercopy.c:27
Read of size 946 at addr ffff88800d3ffff3 by task syz-executor.4/18971

CPU: 1 PID: 18971 Comm: syz-executor.4 Not tainted 4.14.139 #35
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+0x138/0x19c lib/dump_stack.c:53
 print_address_description.cold+0x7c/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2af mm/kasan/report.c:393
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x123/0x190 mm/kasan/kasan.c:267
 kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
 _copy_to_user+0xa4/0xd0 lib/usercopy.c:27
 copy_to_user include/linux/uaccess.h:155 [inline]
 bpf_test_finish.isra.0+0xaf/0x150 net/bpf/test_run.c:59
 bpf_prog_test_run_skb+0x5af/0x9a0 net/bpf/test_run.c:144
 bpf_prog_test_run kernel/bpf/syscall.c:1258 [inline]
 SYSC_bpf kernel/bpf/syscall.c:1520 [inline]
 SyS_bpf+0x749/0x38f3 kernel/bpf/syscall.c:1469
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7
RIP: 0033:0x459829
RSP: 002b:00007fd72964dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000459829
RDX: 0000000000000028 RSI: 00000000200000c0 RDI: 000000000000000a
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd72964e6d4
R13: 00000000004bfb92 R14: 00000000004d1818 R15: 00000000ffffffff

The buggy address belongs to the page:
page:ffffea000034ffc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x1fffc0000000000()
raw: 01fffc0000000000 0000000000000000 0000000000000000 00000000ffffffff
raw: ffffea000034ffe0 ffffea000034ffe0 0000000000000000 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88800d3ffe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88800d3fff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88800d3fff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff88800d400000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88800d400080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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