[syzbot] [fscrypt?] possible deadlock in find_and_lock_process_key

From: syzbot
Date: Sun Nov 26 2023 - 16:10:20 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 9b6de136b5f0 Merge tag 'loongarch-fixes-6.7-1' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11258d67680000
kernel config: https://syzkaller.appspot.com/x/.config?x=aec35c1281ec0aaf
dashboard link: https://syzkaller.appspot.com/bug?extid=9d04b061c581795e18ce
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-9b6de136.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/434b9bf68626/vmlinux-9b6de136.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dd40dbf2926d/bzImage-9b6de136.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9d04b061c581795e18ce@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #0 Not tainted
------------------------------------------------------
syz-executor.1/27256 is trying to acquire lock:
ffffffff8d114b60 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:303 [inline]
ffffffff8d114b60 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slab.h:710 [inline]
ffffffff8d114b60 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slab.c:3221 [inline]
ffffffff8d114b60 (fs_reclaim){+.+.}-{0:0}, at: __kmem_cache_alloc_node+0x42/0x460 mm/slab.c:3521

but task is already holding lock:
ffff8880354d2e98 (&type->lock_class#5){++++}-{3:3}, at: find_and_lock_process_key+0x97/0x390 fs/crypto/keysetup_v1.c:112

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&type->lock_class#5){++++}-{3:3}:
down_read+0x9a/0x330 kernel/locking/rwsem.c:1526
find_and_lock_process_key+0x97/0x390 fs/crypto/keysetup_v1.c:112
fscrypt_setup_v1_file_key_via_subscribed_keyrings+0x115/0x2d0 fs/crypto/keysetup_v1.c:310
setup_file_encryption_key fs/crypto/keysetup.c:485 [inline]
fscrypt_setup_encryption_info+0xb69/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d1/0x4b0 fs/crypto/keysetup.c:675
fscrypt_setup_filename+0x238/0xd80 fs/crypto/fname.c:458
ext4_fname_setup_filename+0xa3/0x250 fs/ext4/crypto.c:28
ext4_add_entry+0x32b/0xe40 fs/ext4/namei.c:2403
ext4_rename+0x165e/0x2880 fs/ext4/namei.c:3932
ext4_rename2+0x1bc/0x270 fs/ext4/namei.c:4212
vfs_rename+0x13e0/0x1c30 fs/namei.c:4844
do_renameat2+0xc3c/0xdc0 fs/namei.c:4996
__do_sys_renameat fs/namei.c:5036 [inline]
__se_sys_renameat fs/namei.c:5033 [inline]
__x64_sys_renameat+0xc6/0x100 fs/namei.c:5033
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #2 (jbd2_handle){++++}-{0:0}:
start_this_handle+0x10ff/0x15e0 fs/jbd2/transaction.c:463
jbd2__journal_start+0x391/0x840 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x343/0x5d0 fs/ext4/ext4_jbd2.c:112
ext4_sample_last_mounted fs/ext4/file.c:835 [inline]
ext4_file_open+0x632/0xc80 fs/ext4/file.c:864
do_dentry_open+0x8d6/0x18c0 fs/open.c:948
do_open fs/namei.c:3622 [inline]
path_openat+0x1e5a/0x2c50 fs/namei.c:3779
do_filp_open+0x1de/0x430 fs/namei.c:3809
do_sys_openat2+0x176/0x1e0 fs/open.c:1440
do_sys_open fs/open.c:1455 [inline]
__do_sys_openat fs/open.c:1471 [inline]
__se_sys_openat fs/open.c:1466 [inline]
__x64_sys_openat+0x175/0x210 fs/open.c:1466
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

-> #1 (sb_internal){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1635 [inline]
sb_start_intwrite include/linux/fs.h:1757 [inline]
ext4_evict_inode+0xe5b/0x1a40 fs/ext4/inode.c:212
evict+0x2ed/0x6b0 fs/inode.c:664
iput_final fs/inode.c:1775 [inline]
iput.part.0+0x560/0x7b0 fs/inode.c:1801
iput+0x5c/0x80 fs/inode.c:1791
dentry_unlink_inode+0x292/0x430 fs/dcache.c:401
__dentry_kill+0x3b8/0x640 fs/dcache.c:607
shrink_dentry_list+0x11e/0x4a0 fs/dcache.c:1201
prune_dcache_sb+0xeb/0x150 fs/dcache.c:1282
super_cache_scan+0x327/0x540 fs/super.c:228
do_shrink_slab+0x428/0x1120 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0xa83/0x1310 mm/shrinker.c:626
shrink_one+0x4f7/0x700 mm/vmscan.c:4724
shrink_many mm/vmscan.c:4776 [inline]
lru_gen_shrink_node mm/vmscan.c:4893 [inline]
shrink_node+0x20cd/0x3790 mm/vmscan.c:5833
kswapd_shrink_node mm/vmscan.c:6638 [inline]
balance_pgdat+0x9d2/0x1a90 mm/vmscan.c:6828
kswapd+0x5be/0xbf0 mm/vmscan.c:7088
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242

-> #0 (fs_reclaim){+.+.}-{0:0}:
check_prev_add kernel/locking/lockdep.c:3134 [inline]
check_prevs_add kernel/locking/lockdep.c:3253 [inline]
validate_chain kernel/locking/lockdep.c:3868 [inline]
__lock_acquire+0x2464/0x3b10 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5718
__fs_reclaim_acquire mm/page_alloc.c:3693 [inline]
fs_reclaim_acquire+0x100/0x150 mm/page_alloc.c:3707
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slab.c:3221 [inline]
__kmem_cache_alloc_node+0x42/0x460 mm/slab.c:3521
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0x49/0x90 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
setup_v1_file_key_derived fs/crypto/keysetup_v1.c:278 [inline]
fscrypt_setup_v1_file_key+0x167/0x550 fs/crypto/keysetup_v1.c:299
fscrypt_setup_v1_file_key_via_subscribed_keyrings+0x159/0x2d0 fs/crypto/keysetup_v1.c:321
setup_file_encryption_key fs/crypto/keysetup.c:485 [inline]
fscrypt_setup_encryption_info+0xb69/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d1/0x4b0 fs/crypto/keysetup.c:675
fscrypt_prepare_readdir include/linux/fscrypt.h:1004 [inline]
ext4_readdir+0x1175/0x3730 fs/ext4/dir.c:137
iterate_dir+0x1e5/0x5b0 fs/readdir.c:106
__do_sys_getdents64 fs/readdir.c:405 [inline]
__se_sys_getdents64 fs/readdir.c:390 [inline]
__x64_sys_getdents64+0x14f/0x2e0 fs/readdir.c:390
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b

other info that might help us debug this:

Chain exists of:
fs_reclaim --> jbd2_handle --> &type->lock_class#5

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
rlock(&type->lock_class#5);
lock(jbd2_handle);
lock(&type->lock_class#5);
lock(fs_reclaim);

*** DEADLOCK ***

3 locks held by syz-executor.1/27256:
#0: ffff88802cf39148 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0xe7/0x170 fs/file.c:1177
#1: ffff88810704e6c0 (&type->i_mutex_dir_key#3){++++}-{3:3}, at: iterate_dir+0xe4/0x5b0 fs/readdir.c:99
#2: ffff8880354d2e98 (&type->lock_class#5){++++}-{3:3}, at: find_and_lock_process_key+0x97/0x390 fs/crypto/keysetup_v1.c:112

stack backtrace:
CPU: 2 PID: 27256 Comm: syz-executor.1 Not tainted 6.7.0-rc2-syzkaller-00029-g9b6de136b5f0 #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+0x317/0x400 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:3868 [inline]
__lock_acquire+0x2464/0x3b10 kernel/locking/lockdep.c:5136
lock_acquire kernel/locking/lockdep.c:5753 [inline]
lock_acquire+0x1ae/0x520 kernel/locking/lockdep.c:5718
__fs_reclaim_acquire mm/page_alloc.c:3693 [inline]
fs_reclaim_acquire+0x100/0x150 mm/page_alloc.c:3707
might_alloc include/linux/sched/mm.h:303 [inline]
slab_pre_alloc_hook mm/slab.h:710 [inline]
slab_alloc_node mm/slab.c:3221 [inline]
__kmem_cache_alloc_node+0x42/0x460 mm/slab.c:3521
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0x49/0x90 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
setup_v1_file_key_derived fs/crypto/keysetup_v1.c:278 [inline]
fscrypt_setup_v1_file_key+0x167/0x550 fs/crypto/keysetup_v1.c:299
fscrypt_setup_v1_file_key_via_subscribed_keyrings+0x159/0x2d0 fs/crypto/keysetup_v1.c:321
setup_file_encryption_key fs/crypto/keysetup.c:485 [inline]
fscrypt_setup_encryption_info+0xb69/0x1080 fs/crypto/keysetup.c:590
fscrypt_get_encryption_info+0x3d1/0x4b0 fs/crypto/keysetup.c:675
fscrypt_prepare_readdir include/linux/fscrypt.h:1004 [inline]
ext4_readdir+0x1175/0x3730 fs/ext4/dir.c:137
iterate_dir+0x1e5/0x5b0 fs/readdir.c:106
__do_sys_getdents64 fs/readdir.c:405 [inline]
__se_sys_getdents64 fs/readdir.c:390 [inline]
__x64_sys_getdents64+0x14f/0x2e0 fs/readdir.c:390
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x40/0x110 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7fb94fa7cae9
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:00007fb9507a70c8 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fb94fb9bf80 RCX: 00007fb94fa7cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fb94fac847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fb94fb9bf80 R15: 00007fff154447b8
</TASK>

---
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