[syzbot] [fscrypt?] possible deadlock in fscrypt_setup_encryption_info

From: syzbot
Date: Sat Mar 02 2024 - 21:54:30 EST

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Hello,

syzbot found the following issue on:

HEAD commit: cf1182944c7c Merge tag 'lsm-pr-20240227' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=136f0f4a180000
kernel config: https://syzkaller.appspot.com/x/.config?x=be0288b26c967205
dashboard link: https://syzkaller.appspot.com/bug?extid=8d26c0204f49ec0b3ed0
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-cf118294.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2ca1f7923b9b/vmlinux-cf118294.xz
kernel image: https://storage.googleapis.com/syzbot-assets/6070ed6e6026/bzImage-cf118294.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8d26c0204f49ec0b3ed0@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc6-syzkaller-00021-gcf1182944c7c #0 Not tainted
------------------------------------------------------
syz-executor.0/30319 is trying to acquire lock:
ffff8880569c4080 (&mk->mk_sem){++++}-{3:3}, at: setup_file_encryption_key fs/crypto/keysetup.c:487 [inline]
ffff8880569c4080 (&mk->mk_sem){++++}-{3:3}, at: fscrypt_setup_encryption_info+0x5da/0x1080 fs/crypto/keysetup.c:590

but task is already holding lock:
ffff888024868950 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x10dd/0x15e0 fs/jbd2/transaction.c:463

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (jbd2_handle){++++}-{0:0}:
start_this_handle+0x1103/0x15e0 fs/jbd2/transaction.c:463
jbd2__journal_start+0x395/0x850 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x347/0x5e0 fs/ext4/ext4_jbd2.c:112
ext4_sample_last_mounted fs/ext4/file.c:837 [inline]
ext4_file_open+0x636/0xc80 fs/ext4/file.c:866
do_dentry_open+0x8da/0x18c0 fs/open.c:953
do_open fs/namei.c:3645 [inline]
path_openat+0x1e00/0x29a0 fs/namei.c:3802
do_filp_open+0x1de/0x440 fs/namei.c:3829
do_sys_openat2+0x17a/0x1e0 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1430
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77

-> #2 (sb_internal){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1641 [inline]
sb_start_intwrite include/linux/fs.h:1824 [inline]
ext4_evict_inode+0xe5f/0x1a40 fs/ext4/inode.c:212
evict+0x2ed/0x6c0 fs/inode.c:665
iput_final fs/inode.c:1739 [inline]
iput.part.0+0x563/0x7b0 fs/inode.c:1765
iput+0x5c/0x80 fs/inode.c:1755
dentry_unlink_inode+0x295/0x440 fs/dcache.c:400
__dentry_kill+0x1d0/0x600 fs/dcache.c:603
shrink_kill fs/dcache.c:1048 [inline]
shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075
prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156
super_cache_scan+0x32a/0x550 fs/super.c:221
do_shrink_slab+0x426/0x1120 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0xa87/0x1310 mm/shrinker.c:626
shrink_one+0x493/0x7b0 mm/vmscan.c:4767
shrink_many mm/vmscan.c:4828 [inline]
lru_gen_shrink_node mm/vmscan.c:4929 [inline]
shrink_node+0x214d/0x3750 mm/vmscan.c:5888
kswapd_shrink_node mm/vmscan.c:6693 [inline]
balance_pgdat+0x9d2/0x1a90 mm/vmscan.c:6883
kswapd+0x5be/0xc00 mm/vmscan.c:7143
kthread+0x2c6/0x3b0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1b/0x30 arch/x86/entry/entry_64.S:243

-> #1 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:3692 [inline]
fs_reclaim_acquire+0x104/0x150 mm/page_alloc.c:3706
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slub.c:3761 [inline]
slab_alloc_node mm/slub.c:3842 [inline]
__do_kmalloc_node mm/slub.c:3980 [inline]
__kmalloc_node+0xb8/0x470 mm/slub.c:3988
kmalloc_node include/linux/slab.h:610 [inline]
kzalloc_node include/linux/slab.h:722 [inline]
crypto_alloc_tfmmem.isra.0+0x38/0x110 crypto/api.c:496
crypto_create_tfm_node+0x83/0x320 crypto/api.c:516
crypto_alloc_tfm_node+0x102/0x260 crypto/api.c:623
fscrypt_allocate_skcipher fs/crypto/keysetup.c:106 [inline]
fscrypt_prepare_key+0x92/0x410 fs/crypto/keysetup.c:158
fscrypt_set_per_file_enc_key fs/crypto/keysetup.c:185 [inline]
fscrypt_setup_v2_file_key+0x3fb/0x5f0 fs/crypto/keysetup.c:374
setup_file_encryption_key fs/crypto/keysetup.c:505 [inline]
fscrypt_setup_encryption_info+0xdf1/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d7/0x4b0 fs/crypto/keysetup.c:675
fscrypt_setup_filename+0x238/0xd80 fs/crypto/fname.c:458
__fscrypt_prepare_lookup+0x2c/0xf0 fs/crypto/hooks.c:100
fscrypt_prepare_lookup include/linux/fscrypt.h:979 [inline]
ext4_fname_prepare_lookup+0x1e0/0x350 fs/ext4/crypto.c:48
ext4_lookup_entry fs/ext4/namei.c:1764 [inline]
ext4_lookup+0x14b/0x740 fs/ext4/namei.c:1839
lookup_one_qstr_excl+0x11d/0x190 fs/namei.c:1608
filename_create+0x1ed/0x530 fs/namei.c:3896
do_mkdirat+0xab/0x3a0 fs/namei.c:4141
__do_sys_mkdirat fs/namei.c:4164 [inline]
__se_sys_mkdirat fs/namei.c:4162 [inline]
__x64_sys_mkdirat+0x115/0x170 fs/namei.c:4162
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77

-> #0 (&mk->mk_sem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x244f/0x3b40 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
down_read+0x9a/0x330 kernel/locking/rwsem.c:1526
setup_file_encryption_key fs/crypto/keysetup.c:487 [inline]
fscrypt_setup_encryption_info+0x5da/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d7/0x4b0 fs/crypto/keysetup.c:675
fscrypt_setup_filename+0x238/0xd80 fs/crypto/fname.c:458
ext4_fname_setup_filename+0xa3/0x260 fs/ext4/crypto.c:28
ext4_add_entry+0x2e3/0xdf0 fs/ext4/namei.c:2401
__ext4_link+0x40b/0x570 fs/ext4/namei.c:3474
ext4_link+0x1fb/0x2a0 fs/ext4/namei.c:3515
vfs_link+0x841/0xdf0 fs/namei.c:4608
do_linkat+0x553/0x600 fs/namei.c:4679
__do_sys_linkat fs/namei.c:4707 [inline]
__se_sys_linkat fs/namei.c:4704 [inline]
__x64_sys_linkat+0xf3/0x140 fs/namei.c:4704
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77

other info that might help us debug this:

Chain exists of:
&mk->mk_sem --> sb_internal --> jbd2_handle

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
rlock(jbd2_handle);
lock(sb_internal);
lock(jbd2_handle);
rlock(&mk->mk_sem);

*** DEADLOCK ***

4 locks held by syz-executor.0/30319:
#0: ffff88802486c420 (sb_writers#5){.+.+}-{0:0}, at: filename_create+0x10d/0x530 fs/namei.c:3888
#1: ffff88802f4ff200 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:839 [inline]
#1: ffff88802f4ff200 (&type->i_mutex_dir_key#3/1){+.+.}-{3:3}, at: filename_create+0x1c2/0x530 fs/namei.c:3895
#2: ffff88802f408e00 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: inode_lock include/linux/fs.h:804 [inline]
#2: ffff88802f408e00 (&sb->s_type->i_mutex_key#7){++++}-{3:3}, at: vfs_link+0x655/0xdf0 fs/namei.c:4599
#3: ffff888024868950 (jbd2_handle){++++}-{0:0}, at: start_this_handle+0x10dd/0x15e0 fs/jbd2/transaction.c:463

stack backtrace:
CPU: 2 PID: 30319 Comm: syz-executor.0 Not tainted 6.8.0-rc6-syzkaller-00021-gcf1182944c7c #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
check_noncircular+0x31b/0x400 kernel/locking/lockdep.c:2187
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3869 [inline]
__lock_acquire+0x244f/0x3b40 kernel/locking/lockdep.c:5137
lock_acquire kernel/locking/lockdep.c:5754 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5719
down_read+0x9a/0x330 kernel/locking/rwsem.c:1526
setup_file_encryption_key fs/crypto/keysetup.c:487 [inline]
fscrypt_setup_encryption_info+0x5da/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d7/0x4b0 fs/crypto/keysetup.c:675
fscrypt_setup_filename+0x238/0xd80 fs/crypto/fname.c:458
ext4_fname_setup_filename+0xa3/0x260 fs/ext4/crypto.c:28
ext4_add_entry+0x2e3/0xdf0 fs/ext4/namei.c:2401
__ext4_link+0x40b/0x570 fs/ext4/namei.c:3474
ext4_link+0x1fb/0x2a0 fs/ext4/namei.c:3515
vfs_link+0x841/0xdf0 fs/namei.c:4608
do_linkat+0x553/0x600 fs/namei.c:4679
__do_sys_linkat fs/namei.c:4707 [inline]
__se_sys_linkat fs/namei.c:4704 [inline]
__x64_sys_linkat+0xf3/0x140 fs/namei.c:4704
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f626787dda9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f62685710c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000109
RAX: ffffffffffffffda RBX: 00007f62679abf80 RCX: 00007f626787dda9
RDX: 0000000000000006 RSI: 00000000200003c0 RDI: 0000000000000003
RBP: 00007f62678ca47a R08: 0000000000000000 R09: 0000000000000000
R10: 00000000200004c0 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007f62679abf80 R15: 00007ffcf764da78
</TASK>

---
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