From 12069401d895ff84076a50189ca842c0696b84b2 Mon Sep 17 00:00:00 2001 From: Jesse Gross Date: Tue, 16 Dec 2014 18:25:32 -0800 Subject: [PATCH] geneve: Fix races between socket add and release. Currently, searching for a socket to add a reference to is not synchronized with deletion of sockets. This can result in use after free if there is another operation that is removing a socket at the same time. Solving this requires both holding the appropriate lock and checking the refcount to ensure that it has not already hit zero. Inspired by a related (but not exactly the same) issue in the VXLAN driver. Fixes: 0b5e8b8e ("net: Add Geneve tunneling protocol driver") CC: Andy Zhou Signed-off-by: Jesse Gross Acked-by: Thomas Graf Signed-off-by: David S. Miller --- net/ipv4/geneve.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/net/ipv4/geneve.c b/net/ipv4/geneve.c index 5a47188b01e9..95e47c97585e 100644 --- a/net/ipv4/geneve.c +++ b/net/ipv4/geneve.c @@ -296,6 +296,7 @@ struct geneve_sock *geneve_sock_add(struct net *net, __be16 port, geneve_rcv_t *rcv, void *data, bool no_share, bool ipv6) { + struct geneve_net *gn = net_generic(net, geneve_net_id); struct geneve_sock *gs; gs = geneve_socket_create(net, port, rcv, data, ipv6); @@ -305,15 +306,15 @@ struct geneve_sock *geneve_sock_add(struct net *net, __be16 port, if (no_share) /* Return error if sharing is not allowed. */ return ERR_PTR(-EINVAL); + spin_lock(&gn->sock_lock); gs = geneve_find_sock(net, port); - if (gs) { - if (gs->rcv == rcv) - atomic_inc(&gs->refcnt); - else + if (gs && ((gs->rcv != rcv) || + !atomic_add_unless(&gs->refcnt, 1, 0))) gs = ERR_PTR(-EBUSY); - } else { + spin_unlock(&gn->sock_lock); + + if (!gs) gs = ERR_PTR(-EINVAL); - } return gs; } -- GitLab