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BUG: KASAN: use-after-free in walk_stackframe+0x11c/0x260 arch/riscv/kernel/stacktrace.c:57
Read of size 8 at addr ffffaf8007debec0 by task syz-executor.1/2946

CPU: 0 PID: 2946 Comm: syz-executor.1 Not tainted 5.17.0-rc1-syzkaller-00002-g0966d385830d #0
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff8000a228>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:113
[<ffffffff831668cc>] show_stack+0x34/0x40 arch/riscv/kernel/stacktrace.c:119
[<ffffffff831756ba>] __dump_stack lib/dump_stack.c:88 [inline]
[<ffffffff831756ba>] dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:106
[<ffffffff8047479e>] print_address_description.constprop.0+0x2a/0x330 mm/kasan/report.c:255
[<ffffffff80474d4c>] __kasan_report mm/kasan/report.c:442 [inline]
[<ffffffff80474d4c>] kasan_report+0x184/0x1e0 mm/kasan/report.c:459
[<ffffffff80475b20>] check_region_inline mm/kasan/generic.c:183 [inline]
[<ffffffff80475b20>] __asan_load8+0x6e/0x96 mm/kasan/generic.c:256
[<ffffffff8000a052>] walk_stackframe+0x11c/0x260 arch/riscv/kernel/stacktrace.c:57
[<ffffffff8000a4a4>] arch_stack_walk+0x2c/0x3c arch/riscv/kernel/stacktrace.c:146
[<ffffffff80162ac8>] stack_trace_save+0xa6/0xd8 kernel/stacktrace.c:122
[<ffffffff80473abe>] kasan_save_stack+0x2c/0x58 mm/kasan/common.c:38

The buggy address belongs to the page:
page:ffffaf807a87fa18 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x87feb
flags: 0x8000000000(section=16|node=0|zone=0)
raw: 0000008000000000 ffffaf807aeaa890 ffffaf807aa4a318 0000000000000000
raw: 0000000000000000 ffffaf800b785060 00000000ffffffff 0000000000000000
raw: 00000000000007ff
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 2, migratetype Unmovable, gfp_mask 0x500dc0(GFP_USER|__GFP_ZERO|__GFP_ACCOUNT), pid 2061, ts 960029833300, free_ts 960090611000
 __set_page_owner+0x48/0x136 mm/page_owner.c:183
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0xd0/0x10a mm/page_alloc.c:2427
 prep_new_page mm/page_alloc.c:2434 [inline]
 get_page_from_freelist+0x8da/0x12d8 mm/page_alloc.c:4165
 __alloc_pages+0x150/0x3b6 mm/page_alloc.c:5389
 __alloc_pages_node include/linux/gfp.h:572 [inline]
 alloc_pages_node include/linux/gfp.h:595 [inline]
 alloc_thread_stack_node kernel/fork.c:262 [inline]
 dup_task_struct kernel/fork.c:887 [inline]
 copy_process+0x482/0x3c34 kernel/fork.c:1998
 kernel_clone+0xee/0x920 kernel/fork.c:2555
 kernel_thread+0xf8/0x130 kernel/fork.c:2607
 call_usermodehelper_exec_work kernel/umh.c:174 [inline]
 call_usermodehelper_exec_work+0xc8/0x122 kernel/umh.c:160
 process_one_work+0x654/0xffe kernel/workqueue.c:2307
 worker_thread+0x360/0x8fa kernel/workqueue.c:2454
 kthread+0x19e/0x1fa kernel/kthread.c:377
 ret_from_exception+0x0/0x10
page last free stack trace:
 __reset_page_owner+0x4a/0xea mm/page_owner.c:142
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1352 [inline]
 free_pcp_prepare+0x29c/0x45e mm/page_alloc.c:1404
 free_unref_page_prepare mm/page_alloc.c:3325 [inline]
 free_unref_page+0x6a/0x31e mm/page_alloc.c:3404
 free_the_page mm/page_alloc.c:706 [inline]
 __free_pages+0xe2/0x112 mm/page_alloc.c:5474
 free_thread_stack kernel/fork.c:297 [inline]
 release_task_stack kernel/fork.c:434 [inline]
 put_task_stack+0x1d0/0x2b0 kernel/fork.c:445
 finish_task_switch.isra.0+0x3ce/0x420 kernel/sched/core.c:4898
 context_switch kernel/sched/core.c:4989 [inline]
 __schedule+0x58e/0x118e kernel/sched/core.c:6296
 preempt_schedule_common+0x4e/0xde kernel/sched/core.c:6462
 preempt_schedule+0x34/0x36 kernel/sched/core.c:6487
 __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
 _raw_spin_unlock_irqrestore+0x8c/0x98 kernel/locking/spinlock.c:194
 spin_unlock_irqrestore include/linux/spinlock.h:404 [inline]
 remove_wait_queue+0x9e/0xb4 kernel/sched/wait.c:57
 do_wait+0x442/0x894 kernel/exit.c:1553
 kernel_wait4+0x158/0x296 kernel/exit.c:1691
 __do_sys_wait4+0x14a/0x156 kernel/exit.c:1719
 sys_wait4+0x30/0x40 kernel/exit.c:1715
 ret_from_syscall+0x0/0x2

Memory state around the buggy address:
 ffffaf8007debd80: 00 00 00 00 00 00 00 00 ff ff ff ff 00 00 00 00
 ffffaf8007debe00: 00 00 00 00 ff ff ff ff ff ff ff ff ff ff ff ff
>ffffaf8007debe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffffaf8007debf00: ff ff ff ff f1 f1 f1 f1 00 00 00 f3 f3 f3 f3 f3
 ffffaf8007debf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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