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BUG: KASAN: stack-out-of-bounds in user_mode arch/x86/include/asm/ptrace.h:131 [inline]
BUG: KASAN: stack-out-of-bounds in unwind_next_frame+0x1be/0x27b0 arch/x86/kernel/unwind_orc.c:421
Read of size 8 at addr ffff8881b164fbd0 by task syz-executor.3/5763

CPU: 1 PID: 5763 Comm: syz-executor.3 Not tainted 5.4.125-syzkaller-00234-g47fe7966921f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1d8/0x24e lib/dump_stack.c:118
 print_address_description+0x9b/0x650 mm/kasan/report.c:384
 __kasan_report+0x182/0x260 mm/kasan/report.c:516
 kasan_report+0x30/0x60 mm/kasan/common.c:653
 user_mode arch/x86/include/asm/ptrace.h:131 [inline]
 unwind_next_frame+0x1be/0x27b0 arch/x86/kernel/unwind_orc.c:421
 arch_stack_walk+0x114/0x140 arch/x86/kernel/stacktrace.c:25
 stack_trace_save_tsk+0x17c/0x270 kernel/stacktrace.c:151
 proc_pid_stack+0x126/0x1f0 fs/proc/base.c:455
 proc_single_show+0xd3/0x120 fs/proc/base.c:757
 seq_read+0x4aa/0xd10 fs/seq_file.c:229
 do_loop_readv_writev fs/read_write.c:714 [inline]
 do_iter_read+0x41b/0x5c0 fs/read_write.c:935
 vfs_readv fs/read_write.c:997 [inline]
 do_preadv+0x20d/0x350 fs/read_write.c:1089
 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x4665d9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f205aa6e188 EFLAGS: 00000246 ORIG_RAX: 0000000000000127
RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665d9
RDX: 000000000000037d RSI: 0000000020000500 RDI: 0000000000000004
RBP: 00000000004bfcb9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056c038
R13: 00007ffc7333969f R14: 00007f205aa6e300 R15: 0000000000022000

The buggy address belongs to the page:
page:ffffea0006c593c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0x8000000000000000()
raw: 8000000000000000 0000000000000000 ffffea0006c59388 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x400dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO)
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook mm/page_alloc.c:2165 [inline]
 prep_new_page+0x19a/0x380 mm/page_alloc.c:2171
 get_page_from_freelist+0x550/0x8b0 mm/page_alloc.c:3794
 __alloc_pages_nodemask+0x3a2/0x880 mm/page_alloc.c:4855
 __alloc_pages include/linux/gfp.h:503 [inline]
 __alloc_pages_node include/linux/gfp.h:516 [inline]
 alloc_pages_node include/linux/gfp.h:530 [inline]
 alloc_thread_stack_node kernel/fork.c:259 [inline]
 dup_task_struct kernel/fork.c:875 [inline]
 copy_process+0x605/0x5630 kernel/fork.c:1877
 _do_fork+0x18f/0x900 kernel/fork.c:2391
 __do_sys_clone kernel/fork.c:2549 [inline]
 __se_sys_clone kernel/fork.c:2530 [inline]
 __x64_sys_clone+0x25b/0x2c0 kernel/fork.c:2530
 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1176 [inline]
 __free_pages_ok+0xc60/0xd80 mm/page_alloc.c:1438
 free_the_page mm/page_alloc.c:4917 [inline]
 __free_pages+0x8f/0x250 mm/page_alloc.c:4923
 free_thread_stack kernel/fork.c:299 [inline]
 release_task_stack kernel/fork.c:439 [inline]
 put_task_stack+0x1ed/0x220 kernel/fork.c:450
 finish_task_switch+0x23f/0x550 kernel/sched/core.c:3459
 context_switch kernel/sched/core.c:3591 [inline]
 __schedule+0x9b8/0x1170 kernel/sched/core.c:4287
 schedule+0x13b/0x1d0 kernel/sched/core.c:4355
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x1c6/0x320 kernel/futex.c:2743
 futex_wait+0x33a/0x920 kernel/futex.c:2849
 do_futex+0xff1/0x3750 kernel/futex.c:3888
 __do_sys_futex kernel/futex.c:3949 [inline]
 __se_sys_futex+0x352/0x470 kernel/futex.c:3917
 do_syscall_64+0xcb/0x1e0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Memory state around the buggy address:
 ffff8881b164fa80: 00 00 00 00 f1 f1 f1 f1 00 00 00 00 f2 f2 f2 f2
 ffff8881b164fb00: 00 f3 f3 f3 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881b164fb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff8881b164fc00: f1 f1 f1 f1 00 00 00 00 f2 f2 f2 f2 00 00 00 00
 ffff8881b164fc80: f2 f2 f2 f2 00 00 00 f3 f3 f3 f3 f3 00 00 00 00
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