[syzbot] [crypto?] possible deadlock in crypto_alg_mod_lookup

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: f8f97927abf7 Add linux-next specific files for 20260105
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=12474074580000
kernel config: https://syzkaller.appspot.com/x/.config?x=a0672dd8d69c3235
dashboard link: https://syzkaller.appspot.com/bug?extid=ced80aa1e67e7ceac4ef
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: https://storage.googleapis.com/syzbot-assets/1837bbc8e23e/disk-f8f97927.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/07390717f7e4/vmlinux-f8f97927.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8f4a72ec80dc/bzImage-f8f97927.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ced80a...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Tainted: G L
------------------------------------------------------
syz.0.8101/30017 is trying to acquire lock:
ffffffff8ea2bc10 (crypto_alg_sem){++++}-{4:4}, at: crypto_larval_add crypto/api.c:137 [inline]
ffffffff8ea2bc10 (crypto_alg_sem){++++}-{4:4}, at: crypto_larval_lookup crypto/api.c:316 [inline]
ffffffff8ea2bc10 (crypto_alg_sem){++++}-{4:4}, at: crypto_alg_mod_lookup+0x211/0x5f0 crypto/api.c:353

but task is already holding lock:
ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1700 [inline]
ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: do_tls_setsockopt net/tls/tls_main.c:871 [inline]
ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: tls_setsockopt+0x384/0x1600 net/tls/tls_main.c:905

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #8 (sk_lock-AF_INET6){+.+.}-{0:0}:
lock_sock_nested+0x48/0x100 net/core/sock.c:3780
lock_sock include/net/sock.h:1700 [inline]
inet_shutdown+0x6a/0x390 net/ipv4/af_inet.c:913
nbd_mark_nsock_dead+0x2e9/0x560 drivers/block/nbd.c:318
recv_work+0x1b38/0x1c50 drivers/block/nbd.c:1021
process_one_work+0x93a/0x15a0 kernel/workqueue.c:3279
process_scheduled_works kernel/workqueue.c:3362 [inline]
worker_thread+0x9b0/0xee0 kernel/workqueue.c:3443
kthread+0x389/0x480 kernel/kthread.c:467
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #7 (&nsock->tx_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:614 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776
nbd_handle_cmd drivers/block/nbd.c:1143 [inline]
nbd_queue_rq+0x257/0xf10 drivers/block/nbd.c:1207
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2135
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
__blk_mq_sched_dispatch_requests+0xdac/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2373
blk_mq_dispatch_list+0xd0b/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2984
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d0/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2eb/0xa30 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x7b7/0x830 fs/buffer.c:2461
filemap_read_folio+0x117/0x380 mm/filemap.c:2496
do_read_cache_folio+0x358/0x590 mm/filemap.c:4096
read_mapping_folio include/linux/pagemap.h:1028 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:765
bdev_open+0x31e/0xd30 block/bdev.c:974
blkdev_open+0x457/0x600 block/fops.c:698
do_dentry_open+0x785/0x14e0 fs/open.c:962
vfs_open+0x3b/0x340 fs/open.c:1094
do_open fs/namei.c:4627 [inline]
path_openat+0x2de0/0x3840 fs/namei.c:4786
do_filp_open+0x1fa/0x410 fs/namei.c:4813
do_sys_openat2+0x121/0x200 fs/open.c:1391
do_sys_open fs/open.c:1397 [inline]
__do_sys_openat fs/open.c:1413 [inline]
__se_sys_openat fs/open.c:1408 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1408
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #6 (&cmd->lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:614 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776
nbd_queue_rq+0xc8/0xf10 drivers/block/nbd.c:1199
blk_mq_dispatch_rq_list+0x4c0/0x1900 block/blk-mq.c:2135
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:168 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:182 [inline]
__blk_mq_sched_dispatch_requests+0xdac/0x1570 block/blk-mq-sched.c:307
blk_mq_sched_dispatch_requests+0xd7/0x190 block/blk-mq-sched.c:329
blk_mq_run_hw_queue+0x348/0x4f0 block/blk-mq.c:2373
blk_mq_dispatch_list+0xd0b/0xe00 include/linux/spinlock.h:-1
blk_mq_flush_plug_list+0x469/0x550 block/blk-mq.c:2984
__blk_flush_plug+0x3d3/0x4b0 block/blk-core.c:1225
blk_finish_plug block/blk-core.c:1252 [inline]
__submit_bio+0x2d0/0x5a0 block/blk-core.c:651
__submit_bio_noacct_mq block/blk-core.c:724 [inline]
submit_bio_noacct_nocheck+0x2eb/0xa30 block/blk-core.c:755
submit_bh fs/buffer.c:2829 [inline]
block_read_full_folio+0x7b7/0x830 fs/buffer.c:2461
filemap_read_folio+0x117/0x380 mm/filemap.c:2496
do_read_cache_folio+0x358/0x590 mm/filemap.c:4096
read_mapping_folio include/linux/pagemap.h:1028 [inline]
read_part_sector+0xb6/0x2b0 block/partitions/core.c:722
adfspart_check_ICS+0xa4/0xa50 block/partitions/acorn.c:360
check_partition block/partitions/core.c:141 [inline]
blk_add_partitions block/partitions/core.c:589 [inline]
bdev_disk_changed+0x75f/0x14b0 block/partitions/core.c:693
blkdev_get_whole+0x380/0x510 block/bdev.c:765
bdev_open+0x31e/0xd30 block/bdev.c:974
blkdev_open+0x457/0x600 block/fops.c:698
do_dentry_open+0x785/0x14e0 fs/open.c:962
vfs_open+0x3b/0x340 fs/open.c:1094
do_open fs/namei.c:4627 [inline]
path_openat+0x2de0/0x3840 fs/namei.c:4786
do_filp_open+0x1fa/0x410 fs/namei.c:4813
do_sys_openat2+0x121/0x200 fs/open.c:1391
do_sys_open fs/open.c:1397 [inline]
__do_sys_openat fs/open.c:1413 [inline]
__se_sys_openat fs/open.c:1408 [inline]
__x64_sys_openat+0x138/0x170 fs/open.c:1408
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #5 (set->srcu){.+.+}-{0:0}:
srcu_lock_sync include/linux/srcu.h:197 [inline]
__synchronize_srcu+0x96/0x390 kernel/rcu/srcutree.c:1503
elevator_switch+0x12b/0x5f0 block/elevator.c:576
elevator_change+0x2cd/0x450 block/elevator.c:680
elevator_set_default+0x1af/0x2b0 block/elevator.c:753
blk_register_queue+0x34e/0x3f0 block/blk-sysfs.c:932
__add_disk+0x677/0xd50 block/genhd.c:528
add_disk_fwnode+0xfc/0x480 block/genhd.c:597
add_disk include/linux/blkdev.h:785 [inline]
nbd_dev_add+0x717/0xae0 drivers/block/nbd.c:1984
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
do_one_initcall+0x1f1/0x800 init/main.c:1378
do_initcall_level+0x104/0x190 init/main.c:1440
do_initcalls+0x59/0xa0 init/main.c:1456
kernel_init_freeable+0x2a7/0x3d0 init/main.c:1688
kernel_init+0x1d/0x1d0 init/main.c:1578
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #4 (&q->elevator_lock){+.+.}-{4:4}:
__mutex_lock_common kernel/locking/mutex.c:614 [inline]
__mutex_lock+0x187/0x1350 kernel/locking/mutex.c:776
elevator_change+0x1b4/0x450 block/elevator.c:678
elevator_set_none+0x98/0x110 block/elevator.c:768
blk_mq_elv_switch_none block/blk-mq.c:5085 [inline]
__blk_mq_update_nr_hw_queues block/blk-mq.c:5129 [inline]
blk_mq_update_nr_hw_queues+0x5b4/0x1a80 block/blk-mq.c:5187
nbd_start_device+0x17f/0xb10 drivers/block/nbd.c:1489
nbd_start_device_ioctl drivers/block/nbd.c:1548 [inline]
__nbd_ioctl drivers/block/nbd.c:1623 [inline]
nbd_ioctl+0x56e/0xe10 drivers/block/nbd.c:1663
blkdev_ioctl+0x60e/0x710 block/ioctl.c:792
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&q->q_usage_counter(io)#53){++++}-{0:0}:
blk_alloc_queue+0x52f/0x610 block/blk-core.c:461
blk_mq_alloc_queue block/blk-mq.c:4416 [inline]
__blk_mq_alloc_disk+0x15c/0x340 block/blk-mq.c:4463
nbd_dev_add+0x46c/0xae0 drivers/block/nbd.c:1954
nbd_init+0x168/0x1f0 drivers/block/nbd.c:2692
do_one_initcall+0x1f1/0x800 init/main.c:1378
do_initcall_level+0x104/0x190 init/main.c:1440
do_initcalls+0x59/0xa0 init/main.c:1456
kernel_init_freeable+0x2a7/0x3d0 init/main.c:1688
kernel_init+0x1d/0x1d0 init/main.c:1578
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #2 (fs_reclaim){+.+.}-{0:0}:
__fs_reclaim_acquire mm/page_alloc.c:4304 [inline]
fs_reclaim_acquire+0x72/0x100 mm/page_alloc.c:4318
might_alloc include/linux/sched/mm.h:317 [inline]
slab_pre_alloc_hook mm/slub.c:4904 [inline]
slab_alloc_node mm/slub.c:5243 [inline]
__kmalloc_cache_noprof+0x40/0x700 mm/slub.c:5775
kmalloc_noprof include/linux/slab.h:957 [inline]
kzalloc_noprof include/linux/slab.h:1094 [inline]
cryptomgr_schedule_probe crypto/algboss.c:87 [inline]
cryptomgr_notify+0x85/0x930 crypto/algboss.c:225
notifier_call_chain+0x19d/0x3a0 kernel/notifier.c:85
blocking_notifier_call_chain+0x6a/0x90 kernel/notifier.c:380
crypto_probing_notify crypto/api.c:327 [inline]
crypto_alg_mod_lookup+0x3b1/0x5f0 crypto/api.c:357
crypto_find_alg crypto/api.c:599 [inline]
crypto_alloc_tfm_node+0x13e/0x3f0 crypto/api.c:636
crypto_alloc_tfm crypto/internal.h:149 [inline]
crypto_alloc_sync_skcipher+0x39/0xd0 crypto/skcipher.c:653
rxkad_init+0x20/0xe0 net/rxrpc/rxkad.c:1309
rxrpc_init_security+0x72/0x120 net/rxrpc/security.c:34
af_rxrpc_init+0x121/0x2d0 net/rxrpc/af_rxrpc.c:1060
do_one_initcall+0x1f1/0x800 init/main.c:1378
do_initcall_level+0x104/0x190 init/main.c:1440
do_initcalls+0x59/0xa0 init/main.c:1456
kernel_init_freeable+0x2a7/0x3d0 init/main.c:1688
kernel_init+0x1d/0x1d0 init/main.c:1578
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #1 ((crypto_chain).rwsem){++++}-{4:4}:
down_read+0x47/0x2e0 kernel/locking/rwsem.c:1537
blocking_notifier_call_chain+0x54/0x90 kernel/notifier.c:379
__crypto_register_alg+0x32b/0x3c0 crypto/algapi.c:346
crypto_register_alg+0x437/0x800 crypto/algapi.c:455
crypto_register_shash crypto/shash.c:529 [inline]
crypto_register_shashes+0x5a/0x100 crypto/shash.c:544
do_one_initcall+0x1f1/0x800 init/main.c:1378
do_initcall_level+0x104/0x190 init/main.c:1440
do_initcalls+0x59/0xa0 init/main.c:1456
kernel_init_freeable+0x2a7/0x3d0 init/main.c:1688
kernel_init+0x1d/0x1d0 init/main.c:1578
ret_from_fork+0x510/0xa50 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

-> #0 (crypto_alg_sem){++++}-{4:4}:
check_prev_add kernel/locking/lockdep.c:3165 [inline]
check_prevs_add kernel/locking/lockdep.c:3284 [inline]
validate_chain kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
crypto_larval_add crypto/api.c:137 [inline]
crypto_larval_lookup crypto/api.c:316 [inline]
crypto_alg_mod_lookup+0x211/0x5f0 crypto/api.c:353
crypto_find_alg crypto/api.c:599 [inline]
crypto_alloc_tfm_node+0x13e/0x3f0 crypto/api.c:636
tls_set_sw_offload+0xa33/0x1780 net/tls/tls_sw.c:2839
do_tls_setsockopt_conf net/tls/tls_main.c:740 [inline]
do_tls_setsockopt net/tls/tls_main.c:872 [inline]
tls_setsockopt+0xefe/0x1600 net/tls/tls_main.c:905
do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2337
__sys_setsockopt net/socket.c:2362 [inline]
__do_sys_setsockopt net/socket.c:2368 [inline]
__se_sys_setsockopt net/socket.c:2365 [inline]
__x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2365
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
crypto_alg_sem --> &nsock->tx_lock --> sk_lock-AF_INET6

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sk_lock-AF_INET6);
lock(&nsock->tx_lock);
lock(sk_lock-AF_INET6);
lock(crypto_alg_sem);

*** DEADLOCK ***

1 lock held by syz.0.8101/30017:
#0: ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: lock_sock include/net/sock.h:1700 [inline]
#0: ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: do_tls_setsockopt net/tls/tls_main.c:871 [inline]
#0: ffff88801fb4df20 (sk_lock-AF_INET6){+.+.}-{0:0}, at: tls_setsockopt+0x384/0x1600 net/tls/tls_main.c:905

stack backtrace:
CPU: 1 UID: 0 PID: 30017 Comm: syz.0.8101 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
print_circular_bug+0x2e2/0x300 kernel/locking/lockdep.c:2043
check_noncircular+0x12e/0x150 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 kernel/locking/lockdep.c:3908 [inline]
__lock_acquire+0x15a6/0x2cf0 kernel/locking/lockdep.c:5237
lock_acquire+0x107/0x340 kernel/locking/lockdep.c:5868
down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590
crypto_larval_add crypto/api.c:137 [inline]
crypto_larval_lookup crypto/api.c:316 [inline]
crypto_alg_mod_lookup+0x211/0x5f0 crypto/api.c:353
crypto_find_alg crypto/api.c:599 [inline]
crypto_alloc_tfm_node+0x13e/0x3f0 crypto/api.c:636
tls_set_sw_offload+0xa33/0x1780 net/tls/tls_sw.c:2839
do_tls_setsockopt_conf net/tls/tls_main.c:740 [inline]
do_tls_setsockopt net/tls/tls_main.c:872 [inline]
tls_setsockopt+0xefe/0x1600 net/tls/tls_main.c:905
do_sock_setsockopt+0x17c/0x1b0 net/socket.c:2337
__sys_setsockopt net/socket.c:2362 [inline]
__do_sys_setsockopt net/socket.c:2368 [inline]
__se_sys_setsockopt net/socket.c:2365 [inline]
__x64_sys_setsockopt+0x13f/0x1b0 net/socket.c:2365
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f86bdb8f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f86bea17038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 00007f86bdde5fa0 RCX: 00007f86bdb8f749
RDX: 0000000000000002 RSI: 000000000000011a RDI: 0000000000000003
RBP: 00007f86bdc13f91 R08: 0000000000000028 R09: 0000000000000000
R10: 0000200000000140 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f86bdde6038 R14: 00007f86bdde5fa0 R15: 00007ffce8b79188
</TASK>


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