From: Dmitry Vyukov Subject: Re: crypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex Date: Sun, 5 Mar 2017 18:36:12 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: syzkaller To: Herbert Xu , David Miller , linux-crypto@vger.kernel.org, LKML , Eric Dumazet , Cong Wang , netdev Return-path: In-Reply-To: Sender: netdev-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Sun, Mar 5, 2017 at 4:08 PM, Dmitry Vyukov wrote: > 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: [] > __netlink_dump_start+0xf4/0x760 net/netlink/af_netlink.c:2187 > > but task is already holding lock: > (crypto_alg_sem){+++++.}, at: [] > 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: [] > crypto_netlink_rcv+0x1b/0x40 crypto/crypto_user.c:537 > #1: (crypto_alg_sem){+++++.}, at: [] > 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 Another one involving tcp_md5sig_mutex: ====================================================== [ INFO: possible circular locking dependency detected ] SELinux: unrecognized netlink message: protocol=9 nlmsg_type=2 sclass=netlink_audit_socket pig=4033 comm=syz-executor4 4.10.0+ #5 Not tainted ------------------------------------------------------- syz-executor8/4018 is trying to acquire lock: (crypto_alg_sem){++++++}, at: [] crypto_alg_lookup+0x23/0x50 crypto/api.c:199 but task is already holding lock: (tcp_md5sig_mutex){+.+...}, at: [] tcp_alloc_md5sig_pool+0x4a/0x470 net/ipv4/tcp.c:3196 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (tcp_md5sig_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 tcp_alloc_md5sig_pool+0x4a/0x470 net/ipv4/tcp.c:3196 tcp_md5_do_add+0x1d8/0x5d0 net/ipv4/tcp_ipv4.c:969 tcp_v4_parse_md5_keys+0x1c7/0x2b0 net/ipv4/tcp_ipv4.c:1037 do_tcp_setsockopt.isra.36+0x657/0x20a0 net/ipv4/tcp.c:2668 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 do_syscall_64+0x2e8/0x930 arch/x86/entry/common.c:281 return_from_SYSCALL_64+0x0/0x7a -> #4 (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] do_ip_setsockopt.isra.12+0x301/0x3760 net/ipv4/ip_sockglue.c:653 ip_setsockopt+0x3a/0xb0 net/ipv4/ip_sockglue.c:1265 tcp_setsockopt+0x82/0xd0 net/ipv4/tcp.c:2731 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 (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 nl80211_prepare_wdev_dump.isra.37+0x2c/0x5d0 net/wireless/nl80211.c:548 nl80211_dump_station+0x178/0xd80 net/wireless/nl80211.c:4455 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 -> #2 (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 -> #1 (nlk->cb_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 __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 -> #0 (crypto_alg_sem){++++++}: 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 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_find_alg crypto/api.c:500 [inline] crypto_alloc_tfm+0x101/0x2e0 crypto/api.c:533 crypto_alloc_ahash+0x2c/0x40 crypto/ahash.c:525 __tcp_alloc_md5sig_pool net/ipv4/tcp.c:3158 [inline] tcp_alloc_md5sig_pool+0x85/0x470 net/ipv4/tcp.c:3199 tcp_md5_do_add+0x1d8/0x5d0 net/ipv4/tcp_ipv4.c:969 tcp_v4_parse_md5_keys+0x1c7/0x2b0 net/ipv4/tcp_ipv4.c:1037 do_tcp_setsockopt.isra.36+0x657/0x20a0 net/ipv4/tcp.c:2668 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 do_syscall_64+0x2e8/0x930 arch/x86/entry/common.c:281 return_from_SYSCALL_64+0x0/0x7a other info that might help us debug this: Chain exists of: crypto_alg_sem --> sk_lock-AF_INET --> tcp_md5sig_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(tcp_md5sig_mutex); lock(sk_lock-AF_INET); lock(tcp_md5sig_mutex); lock(crypto_alg_sem); *** DEADLOCK *** 2 locks held by syz-executor8/4018: #0: (sk_lock-AF_INET){+.+.+.}, at: [] lock_sock include/net/sock.h:1460 [inline] #0: (sk_lock-AF_INET){+.+.+.}, at: [] do_tcp_setsockopt.isra.36+0x216/0x20a0 net/ipv4/tcp.c:2466 #1: (tcp_md5sig_mutex){+.+...}, at: [] tcp_alloc_md5sig_pool+0x4a/0x470 net/ipv4/tcp.c:3196 stack backtrace: CPU: 0 PID: 4018 Comm: syz-executor8 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 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_find_alg crypto/api.c:500 [inline] crypto_alloc_tfm+0x101/0x2e0 crypto/api.c:533 crypto_alloc_ahash+0x2c/0x40 crypto/ahash.c:525 __tcp_alloc_md5sig_pool net/ipv4/tcp.c:3158 [inline] tcp_alloc_md5sig_pool+0x85/0x470 net/ipv4/tcp.c:3199 tcp_md5_do_add+0x1d8/0x5d0 net/ipv4/tcp_ipv4.c:969 tcp_v4_parse_md5_keys+0x1c7/0x2b0 net/ipv4/tcp_ipv4.c:1037 do_tcp_setsockopt.isra.36+0x657/0x20a0 net/ipv4/tcp.c:2668 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 do_syscall_64+0x2e8/0x930 arch/x86/entry/common.c:281