From 1215e51edad1272e669172b26aa12aac94810c7f Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Wed, 12 Apr 2017 12:32:13 -0700 Subject: [PATCH] ipv4: fix a deadlock in ip_ra_control Similar to commit 87e9f0315952 ("ipv4: fix a potential deadlock in mcast getsockopt() path"), there is a deadlock scenario for IP_ROUTER_ALERT too: CPU0 CPU1 ---- ---- lock(rtnl_mutex); lock(sk_lock-AF_INET); lock(rtnl_mutex); lock(sk_lock-AF_INET); Fix this by always locking RTNL first on all setsockopt() paths. Note, after this patch ip_ra_lock is no longer needed either. Reported-by: Dmitry Vyukov Tested-by: Andrey Konovalov Signed-off-by: Cong Wang Signed-off-by: David S. Miller --- net/ipv4/ip_sockglue.c | 1 + net/ipv4/ipmr.c | 11 ++--------- net/ipv4/raw.c | 2 ++ 3 files changed, 5 insertions(+), 9 deletions(-) diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index ebd953bc5607..bda318ae9876 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -591,6 +591,7 @@ static bool setsockopt_needs_rtnl(int optname) case MCAST_LEAVE_GROUP: case MCAST_LEAVE_SOURCE_GROUP: case MCAST_UNBLOCK_SOURCE: + case IP_ROUTER_ALERT: return true; } return false; diff --git a/net/ipv4/ipmr.c b/net/ipv4/ipmr.c index c0317c940bcd..b036e85e093b 100644 --- a/net/ipv4/ipmr.c +++ b/net/ipv4/ipmr.c @@ -1278,7 +1278,7 @@ static void mrtsock_destruct(struct sock *sk) struct net *net = sock_net(sk); struct mr_table *mrt; - rtnl_lock(); + ASSERT_RTNL(); ipmr_for_each_table(mrt, net) { if (sk == rtnl_dereference(mrt->mroute_sk)) { IPV4_DEVCONF_ALL(net, MC_FORWARDING)--; @@ -1289,7 +1289,6 @@ static void mrtsock_destruct(struct sock *sk) mroute_clean_tables(mrt, false); } } - rtnl_unlock(); } /* Socket options and virtual interface manipulation. The whole @@ -1353,13 +1352,8 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, if (sk != rcu_access_pointer(mrt->mroute_sk)) { ret = -EACCES; } else { - /* We need to unlock here because mrtsock_destruct takes - * care of rtnl itself and we can't change that due to - * the IP_ROUTER_ALERT setsockopt which runs without it. - */ - rtnl_unlock(); ret = ip_ra_control(sk, 0, NULL); - goto out; + goto out_unlock; } break; case MRT_ADD_VIF: @@ -1470,7 +1464,6 @@ int ip_mroute_setsockopt(struct sock *sk, int optname, char __user *optval, } out_unlock: rtnl_unlock(); -out: return ret; } diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c index 8119e1f66e03..9d943974de2b 100644 --- a/net/ipv4/raw.c +++ b/net/ipv4/raw.c @@ -682,7 +682,9 @@ static void raw_close(struct sock *sk, long timeout) /* * Raw sockets may have direct kernel references. Kill them. */ + rtnl_lock(); ip_ra_control(sk, 0, NULL); + rtnl_unlock(); sk_common_release(sk); } -- 2.30.2