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Subjectcrypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex
Hello,

I am getting the following deadlock reports while running syzkaller
fuzzer on net-next/8d70eeb84ab277377c017af6a21d0a337025dede:

======================================================
[ INFO: possible circular locking dependency detected ]
4.10.0+ #5 Not tainted
-------------------------------------------------------
syz-executor6/6143 is trying to acquire lock:
(nlk->cb_mutex){+.+.+.}, at: [<ffffffff837df634>]
__netlink_dump_start+0xf4/0x760 net/netlink/af_netlink.c:2187

but task is already holding lock:
(crypto_alg_sem){+++++.}, at: [<ffffffff821cd1f6>]
crypto_user_rcv_msg+0x136/0x4f0 crypto/crypto_user.c:507

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (crypto_alg_sem){+++++.}:
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
down_read+0x9b/0x150 kernel/locking/rwsem.c:23
crypto_alg_lookup+0x23/0x50 crypto/api.c:199
crypto_larval_lookup.part.10+0x9a/0x3b0 crypto/api.c:217
crypto_larval_lookup crypto/api.c:211 [inline]
crypto_alg_mod_lookup+0x77/0x1b0 crypto/api.c:270
crypto_alloc_base+0x50/0x1e0 crypto/api.c:416
crypto_alloc_cipher include/linux/crypto.h:1407 [inline]
tcp_fastopen_reset_cipher+0xc2/0x2e0 net/ipv4/tcp_fastopen.c:48
tcp_fastopen_init_key_once+0x114/0x120 net/ipv4/tcp_fastopen.c:29
do_tcp_setsockopt.isra.36+0x140a/0x20a0 net/ipv4/tcp.c:2684
tcp_setsockopt+0xb0/0xd0 net/ipv4/tcp.c:2733
sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2731
SYSC_setsockopt net/socket.c:1786 [inline]
SyS_setsockopt+0x25c/0x390 net/socket.c:1765
entry_SYSCALL_64_fastpath+0x1f/0xc2

-> #3 (sk_lock-AF_INET){+.+.+.}:
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
lock_sock_nested+0xcb/0x120 net/core/sock.c:2536
lock_sock include/net/sock.h:1460 [inline]
rds_tcp_listen_stop+0x57/0x140 net/rds/tcp_listen.c:284
rds_tcp_kill_sock net/rds/tcp.c:529 [inline]
rds_tcp_dev_event+0x383/0xc50 net/rds/tcp.c:568
notifier_call_chain+0x1b5/0x2b0 kernel/notifier.c:93
__raw_notifier_call_chain kernel/notifier.c:394 [inline]
raw_notifier_call_chain+0x2d/0x40 kernel/notifier.c:401
call_netdevice_notifiers_info+0x51/0x90 net/core/dev.c:1646
call_netdevice_notifiers net/core/dev.c:1662 [inline]
netdev_run_todo+0x3b2/0xa30 net/core/dev.c:7530
rtnl_unlock+0xe/0x10 net/core/rtnetlink.c:104
default_device_exit_batch+0x504/0x620 net/core/dev.c:8334
ops_exit_list.isra.6+0x100/0x150 net/core/net_namespace.c:144
cleanup_net+0x551/0xa90 net/core/net_namespace.c:463
process_one_work+0xbd0/0x1c10 kernel/workqueue.c:2096
worker_thread+0x223/0x1990 kernel/workqueue.c:2230
kthread+0x326/0x3f0 kernel/kthread.c:229
ret_from_fork+0x31/0x40 arch/x86/entry/entry_64.S:430

-> #2 (rtnl_mutex){+.+.+.}:
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x172/0x1730 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
rtnl_lock+0x17/0x20 net/core/rtnetlink.c:70
tipc_nl_bearer_dump+0x3ef/0x720 net/tipc/bearer.c:774
genl_lock_dumpit+0x68/0x90 net/netlink/genetlink.c:479
netlink_dump+0x54d/0xd40 net/netlink/af_netlink.c:2127
__netlink_dump_start+0x4e5/0x760 net/netlink/af_netlink.c:2217
genl_family_rcv_msg+0xd9d/0x1040 net/netlink/genetlink.c:546
genl_rcv_msg+0xa6/0x140 net/netlink/genetlink.c:620
netlink_rcv_skb+0x2ab/0x390 net/netlink/af_netlink.c:2298
genl_rcv+0x28/0x40 net/netlink/genetlink.c:631
netlink_unicast_kernel net/netlink/af_netlink.c:1231 [inline]
netlink_unicast+0x514/0x730 net/netlink/af_netlink.c:1257
netlink_sendmsg+0xa9f/0xe50 net/netlink/af_netlink.c:1803
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
sock_write_iter+0x326/0x600 net/socket.c:846
call_write_iter include/linux/fs.h:1733 [inline]
new_sync_write fs/read_write.c:497 [inline]
__vfs_write+0x483/0x740 fs/read_write.c:510
vfs_write+0x187/0x530 fs/read_write.c:558
SYSC_write fs/read_write.c:605 [inline]
SyS_write+0xfb/0x230 fs/read_write.c:597
entry_SYSCALL_64_fastpath+0x1f/0xc2

-> #1 (genl_mutex){+.+.+.}:
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x172/0x1730 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
genl_lock net/netlink/genetlink.c:32 [inline]
genl_lock_dumpit+0x41/0x90 net/netlink/genetlink.c:478
netlink_dump+0x54d/0xd40 net/netlink/af_netlink.c:2127
__netlink_dump_start+0x4e5/0x760 net/netlink/af_netlink.c:2217
genl_family_rcv_msg+0xd9d/0x1040 net/netlink/genetlink.c:546
genl_rcv_msg+0xa6/0x140 net/netlink/genetlink.c:620
netlink_rcv_skb+0x2ab/0x390 net/netlink/af_netlink.c:2298
genl_rcv+0x28/0x40 net/netlink/genetlink.c:631
netlink_unicast_kernel net/netlink/af_netlink.c:1231 [inline]
netlink_unicast+0x514/0x730 net/netlink/af_netlink.c:1257
netlink_sendmsg+0xa9f/0xe50 net/netlink/af_netlink.c:1803
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
sock_write_iter+0x326/0x600 net/socket.c:846
call_write_iter include/linux/fs.h:1733 [inline]
new_sync_write fs/read_write.c:497 [inline]
__vfs_write+0x483/0x740 fs/read_write.c:510
vfs_write+0x187/0x530 fs/read_write.c:558
SYSC_write fs/read_write.c:605 [inline]
SyS_write+0xfb/0x230 fs/read_write.c:597
entry_SYSCALL_64_fastpath+0x1f/0xc2

-> #0 (nlk->cb_mutex){+.+.+.}:
check_prev_add kernel/locking/lockdep.c:1830 [inline]
check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x172/0x1730 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
__netlink_dump_start+0xf4/0x760 net/netlink/af_netlink.c:2187
netlink_dump_start include/linux/netlink.h:165 [inline]
crypto_user_rcv_msg+0x2ad/0x4f0 crypto/crypto_user.c:517
netlink_rcv_skb+0x2ab/0x390 net/netlink/af_netlink.c:2298
crypto_netlink_rcv+0x2a/0x40 crypto/crypto_user.c:538
netlink_unicast_kernel net/netlink/af_netlink.c:1231 [inline]
netlink_unicast+0x514/0x730 net/netlink/af_netlink.c:1257
netlink_sendmsg+0xa9f/0xe50 net/netlink/af_netlink.c:1803
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
___sys_sendmsg+0x8fa/0x9f0 net/socket.c:1985
__sys_sendmsg+0x138/0x300 net/socket.c:2019
SYSC_sendmsg net/socket.c:2030 [inline]
SyS_sendmsg+0x2d/0x50 net/socket.c:2026
entry_SYSCALL_64_fastpath+0x1f/0xc2

other info that might help us debug this:

Chain exists of:
nlk->cb_mutex --> sk_lock-AF_INET --> crypto_alg_sem

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(crypto_alg_sem);
lock(sk_lock-AF_INET);
lock(crypto_alg_sem);
lock(nlk->cb_mutex);

*** DEADLOCK ***

2 locks held by syz-executor6/6143:
#0: (crypto_cfg_mutex){+.+...}, at: [<ffffffff821cad9b>]
crypto_netlink_rcv+0x1b/0x40 crypto/crypto_user.c:537
#1: (crypto_alg_sem){+++++.}, at: [<ffffffff821cd1f6>]
crypto_user_rcv_msg+0x136/0x4f0 crypto/crypto_user.c:507

stack backtrace:
CPU: 0 PID: 6143 Comm: syz-executor6 Not tainted 4.10.0+ #5
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:16 [inline]
dump_stack+0x2ee/0x3ef lib/dump_stack.c:52
print_circular_bug+0x307/0x3b0 kernel/locking/lockdep.c:1204
check_prev_add kernel/locking/lockdep.c:1830 [inline]
check_prevs_add+0xa8f/0x19f0 kernel/locking/lockdep.c:1940
validate_chain kernel/locking/lockdep.c:2267 [inline]
__lock_acquire+0x2149/0x3430 kernel/locking/lockdep.c:3340
lock_acquire+0x2a1/0x630 kernel/locking/lockdep.c:3755
__mutex_lock_common kernel/locking/mutex.c:756 [inline]
__mutex_lock+0x172/0x1730 kernel/locking/mutex.c:893
mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:908
__netlink_dump_start+0xf4/0x760 net/netlink/af_netlink.c:2187
netlink_dump_start include/linux/netlink.h:165 [inline]
crypto_user_rcv_msg+0x2ad/0x4f0 crypto/crypto_user.c:517
netlink_rcv_skb+0x2ab/0x390 net/netlink/af_netlink.c:2298
crypto_netlink_rcv+0x2a/0x40 crypto/crypto_user.c:538
netlink_unicast_kernel net/netlink/af_netlink.c:1231 [inline]
netlink_unicast+0x514/0x730 net/netlink/af_netlink.c:1257
netlink_sendmsg+0xa9f/0xe50 net/netlink/af_netlink.c:1803
sock_sendmsg_nosec net/socket.c:633 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:643
___sys_sendmsg+0x8fa/0x9f0 net/socket.c:1985
__sys_sendmsg+0x138/0x300 net/socket.c:2019
SYSC_sendmsg net/socket.c:2030 [inline]
SyS_sendmsg+0x2d/0x50 net/socket.c:2026
entry_SYSCALL_64_fastpath+0x1f/0xc2

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