netdev - [PATCH net-next 1/2] inet: Don't go into port scan when looking for specific bind port

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Wed, 14 Dec 2016 16:54:15 -0800
From:   Tom Herbert <tom@...bertland.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     <kernel-team@...com>, <jbacik@...com>, <eric.dumazet@...il.com>,
        <raigatgoog@...il.com>
Subject: [PATCH net-next 1/2] inet: Don't go into port scan when looking for specific bind port

inet_csk_get_port is called with port number (snum argument) that may be
zero or nonzero. If it is zero, then the intent is to find an available
ephemeral port number to bind to. If snum is non-zero then the caller
is asking to allocate a specific port number. In the latter case we
never want to perform the scan in ephemeral port range. It is
conceivable that this can happen if the "goto again" in "tb_found:"
is done. This patch adds a check that snum is zero before doing
the "goto again".

Signed-off-by: Tom Herbert <tom@...bertland.com>
---
 net/ipv4/inet_connection_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index d5d3ead..f59838a6 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -212,7 +212,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 			      sk->sk_reuseport &&
 			      !rcu_access_pointer(sk->sk_reuseport_cb) &&
 			      uid_eq(tb->fastuid, uid))) &&
-			    smallest_size != -1 && --attempts >= 0) {
+			    !snum && smallest_size != -1 && --attempts >= 0) {
 				spin_unlock_bh(&head->lock);
 				goto again;
 			}
-- 
2.9.3