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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 ffffaf8020e4fe70 by task syz-executor.1/2038

CPU: 0 PID: 2038 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:ffffaf807af89638 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xa104f
flags: 0xa000000000(section=20|node=0|zone=0)
raw: 000000a000000000 ffffaf807af89448 ffffaf807af89298 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
raw: 00000000000007ff
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x400dc0(GFP_KERNEL_ACCOUNT|__GFP_ZERO), pid 2653, ts 584273844600, free_ts 584284221900
 __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+0x132/0x2a6 mm/mempolicy.c:2271
 __get_free_pages+0x14/0xb2 mm/page_alloc.c:5438
 get_zeroed_page+0x12/0x1a mm/page_alloc.c:5447
 __pud_alloc_one include/asm-generic/pgalloc.h:156 [inline]
 pud_alloc_one arch/riscv/include/asm/pgalloc.h:66 [inline]
 __pud_alloc+0x68/0x1ca mm/memory.c:4853
 pud_alloc include/linux/mm.h:2237 [inline]
 __handle_mm_fault+0x864/0x23a4 mm/memory.c:4640
 handle_mm_fault+0x296/0x674 mm/memory.c:4803
 faultin_page mm/gup.c:944 [inline]
 __get_user_pages+0x444/0x7b4 mm/gup.c:1165
 __get_user_pages_locked mm/gup.c:1350 [inline]
 __get_user_pages_remote+0x156/0x63a mm/gup.c:1996
 get_user_pages_remote+0x5e/0x86 mm/gup.c:2069
 get_arg_page+0xf4/0x282 fs/exec.c:222
 copy_string_kernel+0x13c/0x3ea fs/exec.c:634
 kernel_execve+0x16c/0x288 fs/exec.c:1967
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_pages.part.0+0xe0/0xf6 mm/page_alloc.c:5485
 free_pages+0xe/0x18 mm/page_alloc.c:5482
 __pud_free include/asm-generic/pgalloc.h:178 [inline]
 pud_free arch/riscv/include/asm/pgalloc.h:75 [inline]
 free_pud_range mm/memory.c:300 [inline]
 free_p4d_range mm/memory.c:318 [inline]
 free_pgd_range+0xb56/0xc54 mm/memory.c:398
 free_pgtables+0xf2/0x1c8 mm/memory.c:430
 exit_mmap+0x168/0x412 mm/mmap.c:3179
 __mmput kernel/fork.c:1114 [inline]
 mmput+0xee/0x2c2 kernel/fork.c:1135
 free_bprm+0xbc/0x1de fs/exec.c:1485
 kernel_execve+0x214/0x288 fs/exec.c:1982
 call_usermodehelper_exec_async+0x1c0/0x2dc kernel/umh.c:112
 ret_from_exception+0x0/0x10

Memory state around the buggy address:
 ffffaf8020e4fd00: ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00
 ffffaf8020e4fd80: ff ff ff ff 00 00 00 00 00 00 00 00 ff ff ff ff
>ffffaf8020e4fe00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffffaf8020e4fe80: ff ff ff ff ff ff ff ff f1 f1 f1 f1 00 00 00 f3
 ffffaf8020e4ff00: f3 f3 f3 f3 00 00 00 00 ff ff ff ff 00 00 00 00
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