From: Dmitry Vyukov Subject: Re: crypto: deadlock between crypto_alg_sem/rtnl_mutex/genl_mutex Date: Tue, 14 Mar 2017 10:44:10 +0100 Message-ID: References: <20170314091649.GA711@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Cc: David Miller , linux-crypto@vger.kernel.org, LKML , Eric Dumazet , Cong Wang , netdev , syzkaller To: Herbert Xu Return-path: In-Reply-To: <20170314091649.GA711@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org On Tue, Mar 14, 2017 at 10:16 AM, Herbert Xu wrote: > On Sun, Mar 05, 2017 at 04:08:39PM +0100, Dmitry Vyukov wrote: >> >> -> #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 > > This looks like a false positive. The cb_mutex in #1 is not the > same as the cb_mutex in #0. The cb_mutex in #0 comes is obtained > by crypto_user which uses straight netlink. The cb_mutex in #1 > is a genl netlink socket. > > I'll have a look to see if we can annotate this. Yes, please. Disregarding some reports is not a good way long term.