From f773608026ee1e75e2256e3ad625c222ff6f9305 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Wed, 6 Sep 2017 11:53:29 +0800 Subject: [PATCH] netlink: access nlk groups safely in netlink bind and getname Now there is no lock protecting nlk ngroups/groups' accessing in netlink bind and getname. It's safe from nlk groups' setting in netlink_release, but not from netlink_realloc_groups called by netlink_setsockopt. netlink_lock_table is needed in both netlink bind and getname when accessing nlk groups. Acked-by: Florian Westphal Signed-off-by: Xin Long Signed-off-by: David S. Miller --- net/netlink/af_netlink.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 94a61e602ee7..327807731b44 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -955,7 +955,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, struct net *net = sock_net(sk); struct netlink_sock *nlk = nlk_sk(sk); struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr; - int err; + int err = 0; long unsigned int groups = nladdr->nl_groups; bool bound; @@ -983,6 +983,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, return -EINVAL; } + netlink_lock_table(); if (nlk->netlink_bind && groups) { int group; @@ -993,7 +994,7 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, if (!err) continue; netlink_undo_bind(group, groups, sk); - return err; + goto unlock; } } @@ -1006,12 +1007,13 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, netlink_autobind(sock); if (err) { netlink_undo_bind(nlk->ngroups, groups, sk); - return err; + goto unlock; } } if (!groups && (nlk->groups == NULL || !(u32)nlk->groups[0])) - return 0; + goto unlock; + netlink_unlock_table(); netlink_table_grab(); netlink_update_subscriptions(sk, nlk->subscriptions + @@ -1022,6 +1024,10 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr, netlink_table_ungrab(); return 0; + +unlock: + netlink_unlock_table(); + return err; } static int netlink_connect(struct socket *sock, struct sockaddr *addr, @@ -1079,7 +1085,9 @@ static int netlink_getname(struct socket *sock, struct sockaddr *addr, nladdr->nl_groups = netlink_group_mask(nlk->dst_group); } else { nladdr->nl_pid = nlk->portid; + netlink_lock_table(); nladdr->nl_groups = nlk->groups ? nlk->groups[0] : 0; + netlink_unlock_table(); } return 0; } -- 2.20.1