syzbot

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BUG: KASAN: slab-use-after-free in proc_invalidate_siblings_dcache+0x6a0/0x6b0 fs/proc/inode.c:114
Read of size 8 at addr ffffaf801c58ab18 by task sshd/3177

CPU: 1 UID: 0 PID: 3177 Comm: sshd Not tainted syzkaller #0 PREEMPT 
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff8007afc2>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:149
[<ffffffff800032f8>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:155
[<ffffffff80060e34>] __dump_stack lib/dump_stack.c:94 [inline]
[<ffffffff80060e34>] dump_stack_lvl+0x114/0x1ac lib/dump_stack.c:120
[<ffffffff8000dd02>] print_address_description mm/kasan/report.c:378 [inline]
[<ffffffff8000dd02>] print_report+0x296/0x5bc mm/kasan/report.c:482
[<ffffffff80b4ff44>] kasan_report+0xf0/0x220 mm/kasan/report.c:595
[<ffffffff80b51e46>] __asan_report_load8_noabort+0x12/0x1c mm/kasan/report_generic.c:381
[<ffffffff80eaa394>] proc_invalidate_siblings_dcache+0x6a0/0x6b0 fs/proc/inode.c:114
[<ffffffff80ebf564>] proc_flush_pid+0x20/0x2c fs/proc/base.c:3478
[<ffffffff80156036>] release_task+0xbca/0x18e8 kernel/exit.c:291
[<ffffffff8015840e>] wait_task_zombie kernel/exit.c:1274 [inline]
[<ffffffff8015840e>] wait_consider_task+0x16ba/0x36ec kernel/exit.c:1501
[<ffffffff8015dcbe>] do_wait_thread kernel/exit.c:1564 [inline]
[<ffffffff8015dcbe>] __do_wait+0x1fa/0x7d8 kernel/exit.c:1682
[<ffffffff8015e4a4>] do_wait+0x208/0x6b0 kernel/exit.c:1716
[<ffffffff8015fd66>] kernel_wait4+0x18a/0x5c8 kernel/exit.c:1875
[<ffffffff801602f6>] __do_sys_wait4+0x152/0x160 kernel/exit.c:1903
[<ffffffff8016066e>] __se_sys_wait4 kernel/exit.c:1899 [inline]
[<ffffffff8016066e>] __riscv_sys_wait4+0x8a/0xd8 kernel/exit.c:1899
[<ffffffff80078192>] syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112
[<ffffffff86391c0a>] do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344
[<ffffffff863bb61e>] handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232

Allocated by task 3177:
 stack_trace_save+0xa0/0xd4 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x68 mm/kasan/common.c:57
 kasan_save_track+0x16/0x28 mm/kasan/common.c:78
 kasan_save_alloc_info+0x30/0x40 mm/kasan/generic.c:570
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x7c/0x84 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4953 [inline]
 slab_alloc_node mm/slub.c:5263 [inline]
 kmem_cache_alloc_noprof+0x1f6/0x830 mm/slub.c:5270
 alloc_pid+0xb8/0x1230 kernel/pid.c:183
 copy_process+0x40e0/0x7330 kernel/fork.c:2237
 kernel_clone+0x120/0xe0c kernel/fork.c:2651
 __do_sys_clone+0xfe/0x140 kernel/fork.c:2792
 __se_sys_clone kernel/fork.c:2760 [inline]
 __riscv_sys_clone+0xa0/0x110 kernel/fork.c:2760
 syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112
 do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344
 handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232

Freed by task 1:
 stack_trace_save+0xa0/0xd4 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x68 mm/kasan/common.c:57
 kasan_save_track+0x16/0x28 mm/kasan/common.c:78
 kasan_save_free_info+0x40/0x5c mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5e/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2540 [inline]
 slab_free mm/slub.c:6674 [inline]
 kmem_cache_free+0x208/0x8d0 mm/slub.c:6785
 put_pid.part.0+0xf8/0x138 kernel/pid.c:100
 put_pid+0x24/0x38 kernel/pid.c:94
 proc_free_inode+0x4a/0xbc fs/proc/inode.c:76
 i_callback+0x42/0x90 fs/inode.c:325
 rcu_do_batch kernel/rcu/tree.c:2605 [inline]
 rcu_core+0x950/0x1ce0 kernel/rcu/tree.c:2857
 rcu_core_si+0xc/0x14 kernel/rcu/tree.c:2874
 handle_softirqs+0x442/0x1198 kernel/softirq.c:622
 __do_softirq kernel/softirq.c:656 [inline]
 invoke_softirq kernel/softirq.c:496 [inline]
 __irq_exit_rcu+0x2de/0x534 kernel/softirq.c:723
 irq_exit_rcu+0x10/0xf4 kernel/softirq.c:739
 handle_riscv_irq+0x40/0x4c arch/riscv/kernel/traps.c:446
 call_on_irq_stack+0x32/0x40 arch/riscv/kernel/entry.S:396

Last potentially related work creation:
 stack_trace_save+0xa0/0xd4 kernel/stacktrace.c:122
 kasan_save_stack+0x3e/0x68 mm/kasan/common.c:57
 kasan_record_aux_stack+0xfc/0x170 mm/kasan/generic.c:556
 __call_rcu_common.constprop.0+0x9a/0x99c kernel/rcu/tree.c:3119
 call_rcu+0xc/0x14 kernel/rcu/tree.c:3239
 free_pid+0x254/0x330 kernel/pid.c:147
 free_pids+0x4c/0x90 kernel/pid.c:159
 release_task+0xbe2/0x18e8 kernel/exit.c:295
 wait_task_zombie kernel/exit.c:1274 [inline]
 wait_consider_task+0x16ba/0x36ec kernel/exit.c:1501
 do_wait_thread kernel/exit.c:1564 [inline]
 __do_wait+0x1fa/0x7d8 kernel/exit.c:1682
 do_wait+0x208/0x6b0 kernel/exit.c:1716
 kernel_wait4+0x18a/0x5c8 kernel/exit.c:1875
 __do_sys_wait4+0x152/0x160 kernel/exit.c:1903
 __se_sys_wait4 kernel/exit.c:1899 [inline]
 __riscv_sys_wait4+0x8a/0xd8 kernel/exit.c:1899
 syscall_handler+0x92/0x114 arch/riscv/include/asm/syscall.h:112
 do_trap_ecall_u+0x3d2/0x58c arch/riscv/kernel/traps.c:344
 handle_exception+0x15e/0x16a arch/riscv/kernel/entry.S:232

The buggy address belongs to the object at ffffaf801c58aa80
 which belongs to the cache pid of size 272
The buggy address is located 152 bytes inside of
 freed 272-byte region [ffffaf801c58aa80, ffffaf801c58ab90)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9c58a
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 ffffaf8011e93780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080150015 00000000f5000000 0000000000000000
head: 0ffe000000000040 ffffaf8011e93780 dead000000000100 dead000000000122
head: 0000000000000000 0000000080150015 00000000f5000000 0000000000000000
head: 0ffe000000000001 ffff8d8000716281 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 89386775300, free_ts 0
 __set_page_owner+0x92/0x4b0 mm/page_owner.c:341
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0xe6/0x1d8 mm/page_alloc.c:1884
 prep_new_page mm/page_alloc.c:1892 [inline]
 get_page_from_freelist+0xfbc/0x3ab8 mm/page_alloc.c:3945
 __alloc_frozen_pages_noprof+0x216/0x20c8 mm/page_alloc.c:5240
 alloc_pages_mpol+0x1f0/0x598 mm/mempolicy.c:2486
 alloc_frozen_pages_noprof+0x154/0x2c8 mm/mempolicy.c:2557
 alloc_slab_page mm/slub.c:3075 [inline]
 allocate_slab mm/slub.c:3248 [inline]
 new_slab+0x35a/0x418 mm/slub.c:3302
 ___slab_alloc+0xc80/0x17f0 mm/slub.c:4656
 __slab_alloc.isra.0+0x6c/0x110 mm/slub.c:4779
 __slab_alloc_node mm/slub.c:4855 [inline]
 slab_alloc_node mm/slub.c:5251 [inline]
 kmem_cache_alloc_noprof+0x438/0x830 mm/slub.c:5270
 alloc_pid+0xb8/0x1230 kernel/pid.c:183
 copy_process+0x40e0/0x7330 kernel/fork.c:2237
 kernel_clone+0x120/0xe0c kernel/fork.c:2651
 user_mode_thread+0xd2/0x110 kernel/fork.c:2727
 call_usermodehelper_exec_work kernel/umh.c:171 [inline]
 call_usermodehelper_exec_work+0xca/0x198 kernel/umh.c:157
 process_one_work+0x930/0x1e14 kernel/workqueue.c:3257
page_owner free stack trace missing

Memory state around the buggy address:
 ffffaf801c58aa00: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffffaf801c58aa80: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffffaf801c58ab00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                            ^
 ffffaf801c58ab80: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffffaf801c58ac00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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