From bceaa90240b6019ed73b49965eac7d167610be69 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Mon, 18 Nov 2013 04:20:45 +0100 Subject: inet: prevent leakage of uninitialized memory to user in recv syscalls Only update *addr_len when we actually fill in sockaddr, otherwise we can return uninitialized memory from the stack to the caller in the recvfrom, recvmmsg and recvmsg syscalls. Drop the the (addr_len == NULL) checks because we only get called with a valid addr_len pointer either from sock_common_recvmsg or inet_recvmsg. If a blocking read waits on a socket which is concurrently shut down we now return zero and set msg_msgnamelen to 0. Reported-by: mpb Suggested-by: Eric Dumazet Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- net/ipv4/udp.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) (limited to 'net/ipv4/udp.c') diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 89909dd730dd..998431cd471a 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1235,12 +1235,6 @@ int udp_recvmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg, int is_udplite = IS_UDPLITE(sk); bool slow; - /* - * Check any passed addresses - */ - if (addr_len) - *addr_len = sizeof(*sin); - if (flags & MSG_ERRQUEUE) return ip_recv_error(sk, msg, len); @@ -1302,6 +1296,7 @@ try_again: sin->sin_port = udp_hdr(skb)->source; sin->sin_addr.s_addr = ip_hdr(skb)->saddr; memset(sin->sin_zero, 0, sizeof(sin->sin_zero)); + *addr_len = sizeof(*sin); } if (inet->cmsg_flags) ip_cmsg_recv(msg, skb); -- cgit v1.2.3-59-g8ed1b