syzbot

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BUG: KASAN: slab-use-after-free in proc_invalidate_siblings_dcache+0x6ae/0x6bc fs/proc/inode.c:114
Read of size 8 at addr ffffaf801aba9a18 by task sshd/3175

CPU: 0 UID: 0 PID: 3175 Comm: sshd Not tainted syzkaller #0 PREEMPT 
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff8007b93e>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:149
[<ffffffff80003346>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:155
[<ffffffff80061ac0>] __dump_stack lib/dump_stack.c:94 [inline]
[<ffffffff80061ac0>] dump_stack_lvl+0x12a/0x1a2 lib/dump_stack.c:120
[<ffffffff8000d85c>] print_address_description mm/kasan/report.c:378 [inline]
[<ffffffff8000d85c>] print_report+0x28c/0x59e mm/kasan/report.c:482
[<ffffffff80b7b6f8>] kasan_report+0xf0/0x218 mm/kasan/report.c:595
[<ffffffff80b7d70e>] __asan_report_load8_noabort+0x12/0x1a mm/kasan/report_generic.c:381
[<ffffffff80edbd4c>] proc_invalidate_siblings_dcache+0x6ae/0x6bc fs/proc/inode.c:114
[<ffffffff80ef0fe0>] proc_flush_pid+0x20/0x2a fs/proc/base.c:3478
[<ffffffff8015b7f6>] release_task+0xc26/0x1908 kernel/exit.c:291
[<ffffffff8015dc9c>] wait_task_zombie kernel/exit.c:1274 [inline]
[<ffffffff8015dc9c>] wait_consider_task+0x17c4/0x3922 kernel/exit.c:1501
[<ffffffff8016375c>] do_wait_thread kernel/exit.c:1564 [inline]
[<ffffffff8016375c>] __do_wait+0x1b2/0x7ba kernel/exit.c:1682
[<ffffffff80163f7c>] do_wait+0x218/0x6d0 kernel/exit.c:1716
[<ffffffff801658ae>] kernel_wait4+0x188/0x5b6 kernel/exit.c:1875
[<ffffffff80165e32>] __do_sys_wait4+0x156/0x162 kernel/exit.c:1903
[<ffffffff801661b2>] __se_sys_wait4 kernel/exit.c:1899 [inline]
[<ffffffff801661b2>] __riscv_sys_wait4+0x8a/0xd6 kernel/exit.c:1899
[<ffffffff800789d8>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
[<ffffffff86662f6e>] do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343
[<ffffffff8668cf0e>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198

Allocated by task 3175:
 stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x6a mm/kasan/common.c:56
 kasan_save_track+0x16/0x28 mm/kasan/common.c:77
 kasan_save_alloc_info+0x30/0x3e mm/kasan/generic.c:570
 unpoison_slab_object mm/kasan/common.c:339 [inline]
 __kasan_slab_alloc+0x7c/0x82 mm/kasan/common.c:365
 kasan_slab_alloc include/linux/kasan.h:252 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x1f6/0x80e mm/slub.c:5270
 alloc_pid+0xd8/0x12fe kernel/pid.c:183
 copy_process+0x408e/0x748e kernel/fork.c:2237
 kernel_clone+0x128/0xdb0 kernel/fork.c:2651
 __do_sys_clone+0xfe/0x13e kernel/fork.c:2792
 __se_sys_clone kernel/fork.c:2760 [inline]
 __riscv_sys_clone+0xa0/0x10e kernel/fork.c:2760
 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
 do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343
 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198

Freed by task 3190:
 stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x6a mm/kasan/common.c:56
 kasan_save_track+0x16/0x28 mm/kasan/common.c:77
 kasan_save_free_info+0x40/0x5a mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5e/0x7e mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6668 [inline]
 kmem_cache_free+0x300/0x882 mm/slub.c:6779
 put_pid.part.0+0x104/0x144 kernel/pid.c:100
 put_pid+0x24/0x36 kernel/pid.c:94
 proc_free_inode+0x4a/0xbc fs/proc/inode.c:76
 i_callback+0x42/0x8e fs/inode.c:325
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0xa36/0x1ed2 kernel/rcu/tree.c:2857
 rcu_core_si+0xc/0x14 kernel/rcu/tree.c:2874
 handle_softirqs+0x4b6/0x1336 kernel/softirq.c:622
 __do_softirq+0x12/0x1a kernel/softirq.c:656

Last potentially related work creation:
 stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x6a mm/kasan/common.c:56
 kasan_record_aux_stack+0x114/0x160 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0x9e/0x9de kernel/rcu/tree.c:3119
 call_rcu+0xc/0x14 kernel/rcu/tree.c:3239
 free_pid+0x278/0x354 kernel/pid.c:147
 free_pids+0x4c/0x8a kernel/pid.c:159
 release_task+0xc3e/0x1908 kernel/exit.c:295
 wait_task_zombie kernel/exit.c:1274 [inline]
 wait_consider_task+0x17c4/0x3922 kernel/exit.c:1501
 do_wait_thread kernel/exit.c:1564 [inline]
 __do_wait+0x1b2/0x7ba kernel/exit.c:1682
 do_wait+0x218/0x6d0 kernel/exit.c:1716
 kernel_wait4+0x188/0x5b6 kernel/exit.c:1875
 __do_sys_wait4+0x156/0x162 kernel/exit.c:1903
 __se_sys_wait4 kernel/exit.c:1899 [inline]
 __riscv_sys_wait4+0x8a/0xd6 kernel/exit.c:1899
 syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
 do_trap_ecall_u+0x3d8/0x56c arch/riscv/kernel/traps.c:343
 handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:198

The buggy address belongs to the object at ffffaf801aba9980
 which belongs to the cache pid of size 272
The buggy address is located 152 bytes inside of
 freed 272-byte region [ffffaf801aba9980, ffffaf801aba9a90)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9aba8
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xffe000000000040(head|node=0|zone=0|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 0ffe000000000040 ffffaf8012293780 ffff8d80006ec800 dead000000000002
raw: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
head: 0ffe000000000040 ffffaf8012293780 ffff8d80006ec800 dead000000000002
head: 0000000000000000 0000000000150015 00000000f5000000 0000000000000000
head: 0ffe000000000001 ffff8d80006aea01 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 12, tgid 12 (kworker/u8:0), ts 64693088700, free_ts 0
 __set_page_owner+0x94/0x4c4 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xfc/0x1c4 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x8e0/0x36b0 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x22e/0x211a mm/page_alloc.c:5210
 alloc_pages_mpol+0x1fa/0x5be mm/mempolicy.c:2486
 alloc_frozen_pages_noprof+0x174/0x2f0 mm/mempolicy.c:2557
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x370/0x438 mm/slub.c:3302
 ___slab_alloc+0xda6/0x1a3c mm/slub.c:4656
 __slab_alloc.constprop.0+0x72/0x118 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_noprof+0x334/0x80e mm/slub.c:5270
 alloc_pid+0xd8/0x12fe kernel/pid.c:183
 copy_process+0x408e/0x748e kernel/fork.c:2237
 kernel_clone+0x128/0xdb0 kernel/fork.c:2651
 user_mode_thread+0xd0/0x10c kernel/fork.c:2727
 call_usermodehelper_exec_work kernel/umh.c:171 [inline]
 call_usermodehelper_exec_work+0xd4/0x1ac kernel/umh.c:157
 process_one_work+0x96a/0x1f3a kernel/workqueue.c:3257
page_owner free stack trace missing

Memory state around the buggy address:
 ffffaf801aba9900: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffffaf801aba9980: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffffaf801aba9a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffffaf801aba9a80: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffffaf801aba9b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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