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BUG: KASAN: out-of-bounds in unwind_get_return_address+0x92/0xa0 arch/x86/kernel/unwind_frame.c:17
Read of size 8 at addr ffff8801c86ef880 by task syzkaller059598/3327

CPU: 1 PID: 3327 Comm: syzkaller059598 Not tainted 4.9.73-gf3f3457 #11
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801c84e7188 ffffffff81d922b9 ffffea000721bbc0 ffff8801c86ef880
 0000000000000000 ffff8801c86ef888 0000000000000000 ffff8801c84e71c0
 ffffffff8153bab3 ffff8801c86ef880 0000000000000008 0000000000000000
Call Trace:
 [<ffffffff81d922b9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81d922b9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8153bab3>] print_address_description+0x73/0x280 mm/kasan/report.c:252
 [<ffffffff8153bfd5>] kasan_report_error mm/kasan/report.c:351 [inline]
 [<ffffffff8153bfd5>] kasan_report+0x275/0x360 mm/kasan/report.c:408
 [<ffffffff8153c134>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:429
 [<ffffffff810d3be2>] unwind_get_return_address+0x92/0xa0 arch/x86/kernel/unwind_frame.c:17
 [<ffffffff8107c4fd>] __save_stack_trace+0x8d/0xf0 arch/x86/kernel/stacktrace.c:43
 [<ffffffff8107c5c8>] save_stack_trace_tsk+0x48/0x70 arch/x86/kernel/stacktrace.c:71
 [<ffffffff816c2e66>] proc_pid_stack+0x146/0x230 fs/proc/base.c:466
 [<ffffffff816c4638>] proc_single_show+0xf8/0x170 fs/proc/base.c:768
 [<ffffffff815e676f>] seq_read+0x32f/0x1290 fs/seq_file.c:240
 [<ffffffff8156a4e1>] do_loop_readv_writev.part.17+0x141/0x1e0 fs/read_write.c:714
 [<ffffffff8156e350>] do_loop_readv_writev fs/read_write.c:880 [inline]
 [<ffffffff8156e350>] do_readv_writev+0x520/0x750 fs/read_write.c:874
 [<ffffffff8156e604>] vfs_readv+0x84/0xc0 fs/read_write.c:898
 [<ffffffff8160d6bf>] kernel_readv fs/splice.c:363 [inline]
 [<ffffffff8160d6bf>] default_file_splice_read+0x43f/0x7a0 fs/splice.c:435
 [<ffffffff8160c7ba>] do_splice_to+0x10a/0x160 fs/splice.c:899
 [<ffffffff8160ca5d>] splice_direct_to_actor+0x24d/0x800 fs/splice.c:971
 [<ffffffff8160d1b7>] do_splice_direct+0x1a7/0x270 fs/splice.c:1080
 [<ffffffff815703cb>] do_sendfile+0x54b/0xd30 fs/read_write.c:1401
 [<ffffffff81572481>] C_SYSC_sendfile fs/read_write.c:1477 [inline]
 [<ffffffff81572481>] compat_SyS_sendfile+0xd1/0x160 fs/read_write.c:1466
 [<ffffffff81006fc7>] do_syscall_32_irqs_on arch/x86/entry/common.c:322 [inline]
 [<ffffffff81006fc7>] do_fast_syscall_32+0x2f7/0x890 arch/x86/entry/common.c:384
 [<ffffffff838b0be1>] entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:124

The buggy address belongs to the page:
page:ffffea000721bbc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x8000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801c86ef780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801c86ef800: 00 00 00 f1 f1 f1 f1 00 00 00 00 f3 f3 f3 f3 00
>ffff8801c86ef880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                      ^
 ffff8801c86ef900: 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
 ffff8801c86ef980: 00 00 00 f2 00 00 00 00 00 00 00 00 00 00 00 00
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