[moderation] [fs?] KASAN: slab-use-after-free Read in proc_invalidate_siblings_dcache

0 views
Skip to first unread message

syzbot

unread,
Sep 17, 2025, 10:57:35 PM (2 days ago) Sep 17
to syzkaller-upst...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: 8f5ae30d69d7 Linux 6.17-rc1
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux.git for-next
console output: https://syzkaller.appspot.com/x/log.txt?x=17db9b62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=5a7613f5d8c9cb65
dashboard link: https://syzkaller.appspot.com/bug?extid=ac1bb3c3a644cdb48640
compiler: riscv64-linux-gnu-gcc (Debian 12.2.0-13) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: riscv64
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/a741b348759c/non_bootable_disk-8f5ae30d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b5e2a13645b4/vmlinux-8f5ae30d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3100096abd6f/Image-8f5ae30d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ac1bb3...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: slab-use-after-free in proc_invalidate_siblings_dcache+0x6ae/0x6bc fs/proc/inode.c:114
Read of size 8 at addr ffffaf801b161418 by task sshd/3178

CPU: 1 UID: 0 PID: 3178 Comm: sshd Not tainted 6.17.0-rc1-syzkaller-g8f5ae30d69d7 #0 PREEMPT
Hardware name: riscv-virtio,qemu (DT)
Call Trace:
[<ffffffff8007949a>] dump_backtrace+0x2e/0x3c arch/riscv/kernel/stacktrace.c:132
[<ffffffff8000329a>] show_stack+0x30/0x3c arch/riscv/kernel/stacktrace.c:138
[<ffffffff80060b76>] __dump_stack lib/dump_stack.c:94 [inline]
[<ffffffff80060b76>] dump_stack_lvl+0x12e/0x1a6 lib/dump_stack.c:120
[<ffffffff8000ee40>] print_address_description mm/kasan/report.c:378 [inline]
[<ffffffff8000ee40>] print_report+0x28e/0x5a2 mm/kasan/report.c:482
[<ffffffff80b1ed32>] kasan_report+0xf0/0x214 mm/kasan/report.c:595
[<ffffffff80b20dca>] __asan_report_load8_noabort+0x12/0x1a mm/kasan/report_generic.c:381
[<ffffffff80e6eeda>] proc_invalidate_siblings_dcache+0x6ae/0x6bc fs/proc/inode.c:114
[<ffffffff80e83324>] proc_flush_pid+0x20/0x2a fs/proc/base.c:3483
[<ffffffff80159a0c>] release_task+0xcda/0x1cae kernel/exit.c:293
[<ffffffff8015c1a4>] wait_task_zombie kernel/exit.c:1264 [inline]
[<ffffffff8015c1a4>] wait_consider_task+0x17c4/0x3922 kernel/exit.c:1491
[<ffffffff80161c48>] do_wait_thread kernel/exit.c:1554 [inline]
[<ffffffff80161c48>] __do_wait+0x1b2/0x7ba kernel/exit.c:1672
[<ffffffff80162468>] do_wait+0x218/0x6ca kernel/exit.c:1706
[<ffffffff80163d84>] kernel_wait4+0x188/0x5a6 kernel/exit.c:1865
[<ffffffff801642f8>] __do_sys_wait4+0x156/0x162 kernel/exit.c:1893
[<ffffffff80164678>] __se_sys_wait4 kernel/exit.c:1889 [inline]
[<ffffffff80164678>] __riscv_sys_wait4+0x8a/0xd6 kernel/exit.c:1889
[<ffffffff8007715e>] syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
[<ffffffff863c3c76>] do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343
[<ffffffff863ed596>] handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197

Allocated by task 3178:
stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
kasan_save_stack+0x3e/0x6a mm/kasan/common.c:47
kasan_save_track+0x16/0x28 mm/kasan/common.c:68
kasan_save_alloc_info+0x30/0x3e mm/kasan/generic.c:562
unpoison_slab_object mm/kasan/common.c:330 [inline]
__kasan_slab_alloc+0x7c/0x82 mm/kasan/common.c:356
kasan_slab_alloc include/linux/kasan.h:250 [inline]
slab_post_alloc_hook mm/slub.c:4180 [inline]
slab_alloc_node mm/slub.c:4229 [inline]
kmem_cache_alloc_noprof+0x104/0x3bc mm/slub.c:4236
alloc_pid+0xd8/0x128a kernel/pid.c:183
copy_process+0x426c/0x72da kernel/fork.c:2191
kernel_clone+0x128/0xd9e kernel/fork.c:2605
__do_sys_clone+0xfe/0x13e kernel/fork.c:2748
__se_sys_clone kernel/fork.c:2716 [inline]
__riscv_sys_clone+0xa0/0x10e kernel/fork.c:2716
syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343
handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197

Freed by task 3192:
stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
kasan_save_stack+0x3e/0x6a mm/kasan/common.c:47
kasan_save_track+0x16/0x28 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x5a mm/kasan/generic.c:576
poison_slab_object mm/kasan/common.c:243 [inline]
__kasan_slab_free+0x4a/0x62 mm/kasan/common.c:275
kasan_slab_free include/linux/kasan.h:233 [inline]
slab_free_hook mm/slub.c:2417 [inline]
slab_free mm/slub.c:4680 [inline]
kmem_cache_free+0x2b4/0x562 mm/slub.c:4782
put_pid.part.0+0x104/0x144 kernel/pid.c:104
put_pid+0x24/0x36 kernel/pid.c:98
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+0xa24/0x1ef8 kernel/rcu/tree.c:2861
rcu_core_si+0xc/0x14 kernel/rcu/tree.c:2878
handle_softirqs+0x4b2/0x132e kernel/softirq.c:579
__do_softirq kernel/softirq.c:613 [inline]
invoke_softirq kernel/softirq.c:453 [inline]
__irq_exit_rcu+0x18c/0x550 kernel/softirq.c:680
irq_exit_rcu+0x10/0xf8 kernel/softirq.c:696
handle_riscv_irq+0x40/0x4c arch/riscv/kernel/traps.c:390
call_on_irq_stack+0x32/0x40 arch/riscv/kernel/entry.S:360

Last potentially related work creation:
stack_trace_save+0xa0/0xd2 kernel/stacktrace.c:122
kasan_save_stack+0x3e/0x6a mm/kasan/common.c:47
kasan_record_aux_stack+0x114/0x160 mm/kasan/generic.c:548
__call_rcu_common.constprop.0+0x9e/0x9da kernel/rcu/tree.c:3123
call_rcu+0xc/0x14 kernel/rcu/tree.c:3243
free_pid+0x20a/0x2d0 kernel/pid.c:147
free_pids+0x4c/0x8a kernel/pid.c:159
release_task+0xcf0/0x1cae kernel/exit.c:296
wait_task_zombie kernel/exit.c:1264 [inline]
wait_consider_task+0x17c4/0x3922 kernel/exit.c:1491
do_wait_thread kernel/exit.c:1554 [inline]
__do_wait+0x1b2/0x7ba kernel/exit.c:1672
do_wait+0x218/0x6ca kernel/exit.c:1706
kernel_wait4+0x188/0x5a6 kernel/exit.c:1865
__do_sys_wait4+0x156/0x162 kernel/exit.c:1893
__se_sys_wait4 kernel/exit.c:1889 [inline]
__riscv_sys_wait4+0x8a/0xd6 kernel/exit.c:1889
syscall_handler+0x94/0x118 arch/riscv/include/asm/syscall.h:112
do_trap_ecall_u+0x396/0x530 arch/riscv/kernel/traps.c:343
handle_exception+0x146/0x152 arch/riscv/kernel/entry.S:197

The buggy address belongs to the object at ffffaf801b161380
which belongs to the cache pid of size 272
The buggy address is located 152 bytes inside of
freed 272-byte region [ffffaf801b161380, ffffaf801b161490)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x9b160
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 ffffaf8011a93780 dead000000000100 dead000000000122
raw: 0000000000000000 0000000080150015 00000000f5000000 0000000000000000
head: 0ffe000000000040 ffffaf8011a93780 dead000000000100 dead000000000122
head: 0000000000000000 0000000080150015 00000000f5000000 0000000000000000
head: 0ffe000000000001 ffff8d80006c5801 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 949, tgid 949 (kworker/u9:4), ts 62141947100, free_ts 0
__set_page_owner+0x94/0x4a8 mm/page_owner.c:329
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0xdc/0x1ba mm/page_alloc.c:1851
prep_new_page mm/page_alloc.c:1859 [inline]
get_page_from_freelist+0x7fa/0x359a mm/page_alloc.c:3858
__alloc_frozen_pages_noprof+0x22e/0x2120 mm/page_alloc.c:5148
alloc_pages_mpol+0x1fa/0x5bc mm/mempolicy.c:2416
alloc_frozen_pages_noprof+0x174/0x2f0 mm/mempolicy.c:2487
alloc_slab_page mm/slub.c:2487 [inline]
allocate_slab mm/slub.c:2655 [inline]
new_slab+0x27c/0x38c mm/slub.c:2709
___slab_alloc+0xb5a/0x1192 mm/slub.c:3891
__slab_alloc.constprop.0+0x60/0xb0 mm/slub.c:3981
__slab_alloc_node mm/slub.c:4056 [inline]
slab_alloc_node mm/slub.c:4217 [inline]
kmem_cache_alloc_noprof+0xd0/0x3bc mm/slub.c:4236
alloc_pid+0xd8/0x128a kernel/pid.c:183
copy_process+0x426c/0x72da kernel/fork.c:2191
kernel_clone+0x128/0xd9e kernel/fork.c:2605
user_mode_thread+0xd4/0x110 kernel/fork.c:2683
call_usermodehelper_exec_work kernel/umh.c:171 [inline]
call_usermodehelper_exec_work+0xd4/0x1ac kernel/umh.c:157
process_one_work+0x96a/0x1f32 kernel/workqueue.c:3236
page_owner free stack trace missing

Memory state around the buggy address:
ffffaf801b161300: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffaf801b161380: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffffaf801b161400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffffaf801b161480: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffffaf801b161500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup

Aleksandr Nogikh

unread,
Sep 18, 2025, 6:39:56 AM (yesterday) Sep 18
to syzbot, syzkaller-upst...@googlegroups.com
#syz upstream

--
You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-upstream-m...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/syzkaller-upstream-moderation/68cb751d.050a0220.2ff435.05a1.GAE%40google.com.
Reply all
Reply to author
Forward
0 new messages