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BUG: KASAN: out-of-bounds in unwind_get_return_address+0x96/0xa0 arch/x86/kernel/unwind_frame.c:17
Read of size 8 at addr ffff8801a3caf938 by task syz-executor3/17174

CPU: 1 PID: 17174 Comm: syz-executor3 Not tainted 4.9.154+ #20
 ffff8801ca19f7e8 ffffffff81b47411 0000000000000000 ffffea00068f2bc0
 ffff8801a3caf938 0000000000000008 ffffffff810ab576 ffff8801ca19f820
 ffffffff81502615 0000000000000000 ffff8801a3caf940 ffff8801a3caf938
Call Trace:
 [<ffffffff81b47411>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b47411>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff81502615>] print_address_description+0x6f/0x238 mm/kasan/report.c:256
 [<ffffffff8150286a>] kasan_report_error mm/kasan/report.c:355 [inline]
 [<ffffffff8150286a>] kasan_report mm/kasan/report.c:412 [inline]
 [<ffffffff8150286a>] kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:397
 [<ffffffff814f4a64>] __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
 [<ffffffff810ab576>] unwind_get_return_address+0x96/0xa0 arch/x86/kernel/unwind_frame.c:17
 [<ffffffff8107732a>] __save_stack_trace+0x8a/0xf0 arch/x86/kernel/stacktrace.c:43
 [<ffffffff810773f2>] save_stack_trace_tsk arch/x86/kernel/stacktrace.c:71 [inline]
 [<ffffffff810773f2>] save_stack_trace_tsk+0x42/0x60 arch/x86/kernel/stacktrace.c:66
 [<ffffffff8166a962>] proc_pid_stack+0x1a2/0x290 fs/proc/base.c:483
 [<ffffffff81662f16>] proc_single_show+0xf6/0x160 fs/proc/base.c:785
 [<ffffffff81582edd>] seq_read+0x4cd/0x1250 fs/seq_file.c:240
 [<ffffffff8150bbcc>] do_loop_readv_writev.part.0+0xcc/0x2c0 fs/read_write.c:718
 [<ffffffff8150d2d6>] do_loop_readv_writev fs/read_write.c:707 [inline]
 [<ffffffff8150d2d6>] do_readv_writev+0x556/0x7a0 fs/read_write.c:873
 [<ffffffff8150d5a6>] vfs_readv+0x86/0xc0 fs/read_write.c:897
 [<ffffffff8150d9db>] do_preadv+0x19b/0x240 fs/read_write.c:974
 [<ffffffff81510ec1>] SYSC_preadv fs/read_write.c:1024 [inline]
 [<ffffffff81510ec1>] SyS_preadv+0x31/0x40 fs/read_write.c:1019
 [<ffffffff810056bd>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285
 [<ffffffff82816493>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb

The buggy address belongs to the page:
page:ffffea00068f2bc0 count:0 mapcount:0 mapping:          (null) index:0x0
flags: 0x4000000000000000()
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801a3caf800: 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1 f1
 ffff8801a3caf880: f1 00 00 00 00 f3 f3 f3 f3 00 00 00 00 00 00 00
>ffff8801a3caf900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                           ^
 ffff8801a3caf980: 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00 f3 f3 f3
 ffff8801a3cafa00: f3 f3 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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