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Message-ID: <68e54915.a00a0220.298cc0.0480.GAE@google.com>
Date: Tue, 07 Oct 2025 10:08:37 -0700
From: syzbot <syzbot+f55b043dacf43776b50c@...kaller.appspotmail.com>
To: dhowells@...hat.com, jarkko@...nel.org, jmorris@...ei.org,
keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org, paul@...l-moore.com, serge@...lyn.com,
syzkaller-bugs@...glegroups.com
Subject: [syzbot] [keyrings?] [lsm?] possible deadlock in keyring_clear (3)
Hello,
syzbot found the following issue on:
HEAD commit: cbf33b8e0b36 Merge tag 'bpf-fixes' of git://git.kernel.org..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1036c458580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1b4263e12240e6e1
dashboard link: https://syzkaller.appspot.com/bug?extid=f55b043dacf43776b50c
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
Unfortunately, I don't have any reproducer for this issue yet.
Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-cbf33b8e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/54786e46ef23/vmlinux-cbf33b8e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd6f88ce083b/bzImage-cbf33b8e.xz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f55b043dacf43776b50c@...kaller.appspotmail.com
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/74 is trying to acquire lock:
ffff8880420f4098 (&type->lock_class){+.+.}-{4:4}, at: keyring_clear+0xaf/0x240 security/keys/keyring.c:1658
but task is already holding lock:
ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline]
ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (fs_reclaim){+.+.}-{0:0}:
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
__fs_reclaim_acquire mm/page_alloc.c:4269 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4283
might_alloc include/linux/sched/mm.h:318 [inline]
slab_pre_alloc_hook mm/slub.c:4897 [inline]
slab_alloc_node mm/slub.c:5221 [inline]
__kmalloc_cache_noprof+0x40/0x6f0 mm/slub.c:5719
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
assoc_array_insert+0x92/0x2f90 lib/assoc_array.c:980
__key_link_begin+0xd6/0x1f0 security/keys/keyring.c:1317
__key_create_or_update+0x41a/0xa30 security/keys/key.c:877
key_create_or_update+0x42/0x60 security/keys/key.c:1021
x509_load_certificate_list+0x145/0x280 crypto/asymmetric_keys/x509_loader.c:31
do_one_initcall+0x233/0x820 init/main.c:1283
do_initcall_level+0x104/0x190 init/main.c:1345
do_initcalls+0x59/0xa0 init/main.c:1361
kernel_init_freeable+0x334/0x4b0 init/main.c:1593
kernel_init+0x1d/0x1d0 init/main.c:1483
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
-> #0 (&type->lock_class){+.+.}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
keyring_clear+0xaf/0x240 security/keys/keyring.c:1658
fscrypt_put_master_key+0xca/0x190 fs/crypto/keyring.c:80
put_crypt_info+0x26d/0x310 fs/crypto/keysetup.c:573
fscrypt_put_encryption_info+0xf6/0x140 fs/crypto/keysetup.c:787
ext4_clear_inode+0x170/0x2f0 fs/ext4/super.c:1527
ext4_evict_inode+0xa67/0xee0 fs/ext4/inode.c:321
evict+0x504/0x9c0 fs/inode.c:810
dispose_list fs/inode.c:852 [inline]
prune_icache_sb+0x21b/0x2c0 fs/inode.c:1000
super_cache_scan+0x39b/0x4b0 fs/super.c:224
do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x28a/0x7c0 mm/vmscan.c:4955
shrink_many mm/vmscan.c:5016 [inline]
lru_gen_shrink_node mm/vmscan.c:5094 [inline]
shrink_node+0x315d/0x3780 mm/vmscan.c:6081
kswapd_shrink_node mm/vmscan.c:6941 [inline]
balance_pgdat mm/vmscan.c:7124 [inline]
kswapd+0x147c/0x2800 mm/vmscan.c:7389
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&type->lock_class);
lock(fs_reclaim);
lock(&type->lock_class);
*** DEADLOCK ***
2 locks held by kswapd0/74:
#0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:7015 [inline]
#0: ffffffff8de44f40 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0x951/0x2800 mm/vmscan.c:7389
#1: ffff8880115840e0 (&type->s_umount_key#31){++++}-{4:4}, at: super_trylock_shared fs/super.c:562 [inline]
#1: ffff8880115840e0 (&type->s_umount_key#31){++++}-{4:4}, at: super_cache_scan+0x91/0x4b0 fs/super.c:197
stack backtrace:
CPU: 0 UID: 0 PID: 74 Comm: kswapd0 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043
check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2175
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908
__lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237
lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
keyring_clear+0xaf/0x240 security/keys/keyring.c:1658
fscrypt_put_master_key+0xca/0x190 fs/crypto/keyring.c:80
put_crypt_info+0x26d/0x310 fs/crypto/keysetup.c:573
fscrypt_put_encryption_info+0xf6/0x140 fs/crypto/keysetup.c:787
ext4_clear_inode+0x170/0x2f0 fs/ext4/super.c:1527
ext4_evict_inode+0xa67/0xee0 fs/ext4/inode.c:321
evict+0x504/0x9c0 fs/inode.c:810
dispose_list fs/inode.c:852 [inline]
prune_icache_sb+0x21b/0x2c0 fs/inode.c:1000
super_cache_scan+0x39b/0x4b0 fs/super.c:224
do_shrink_slab+0x6ef/0x1110 mm/shrinker.c:437
shrink_slab_memcg mm/shrinker.c:550 [inline]
shrink_slab+0x7ef/0x10d0 mm/shrinker.c:628
shrink_one+0x28a/0x7c0 mm/vmscan.c:4955
shrink_many mm/vmscan.c:5016 [inline]
lru_gen_shrink_node mm/vmscan.c:5094 [inline]
shrink_node+0x315d/0x3780 mm/vmscan.c:6081
kswapd_shrink_node mm/vmscan.c:6941 [inline]
balance_pgdat mm/vmscan.c:7124 [inline]
kswapd+0x147c/0x2800 mm/vmscan.c:7389
kthread+0x70e/0x8a0 kernel/kthread.c:463
ret_from_fork+0x436/0x7d0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
---
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 syzkaller@...glegroups.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
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