linux-kernel - [PATCH 3.2 14/74] af_iucv: Move sockaddr length checks to before accessing sa

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Message-ID: <lsq.1507552234.218195992@decadent.org.uk>
Date:   Mon, 09 Oct 2017 13:30:34 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Mateusz Jurczyk" <mjurczyk@...gle.com>,
        "Julian Wiedmann" <jwi@...ux.vnet.ibm.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 3.2 14/74] af_iucv: Move sockaddr length checks to before
 accessing sa_family in bind and connect handlers

3.2.94-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mateusz Jurczyk <mjurczyk@...gle.com>

commit e3c42b61ff813921ba58cfc0019e3fd63f651190 upstream.

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() and connect()
handlers of the AF_IUCV socket. Since neither syscall enforces a minimum
size of the corresponding memory region, very short sockaddrs (zero or
one byte long) result in operating on uninitialized memory while
referencing .sa_family.

Fixes: 52a82e23b9f2 ("af_iucv: Validate socket address length in iucv_sock_bind()")
Signed-off-by: Mateusz Jurczyk <mjurczyk@...gle.com>
[jwi: removed unneeded null-check for addr]
Signed-off-by: Julian Wiedmann <jwi@...ux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/iucv/af_iucv.c | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -705,10 +705,8 @@ static int iucv_sock_bind(struct socket
 	char uid[9];
 
 	/* Verify the input sockaddr */
-	if (!addr || addr->sa_family != AF_IUCV)
-		return -EINVAL;
-
-	if (addr_len < sizeof(struct sockaddr_iucv))
+	if (addr_len < sizeof(struct sockaddr_iucv) ||
+	    addr->sa_family != AF_IUCV)
 		return -EINVAL;
 
 	lock_sock(sk);
@@ -879,7 +877,7 @@ static int iucv_sock_connect(struct sock
 	struct iucv_sock *iucv = iucv_sk(sk);
 	int err;
 
-	if (addr->sa_family != AF_IUCV || alen < sizeof(struct sockaddr_iucv))
+	if (alen < sizeof(struct sockaddr_iucv) || addr->sa_family != AF_IUCV)
 		return -EINVAL;
 
 	if (sk->sk_state != IUCV_OPEN && sk->sk_state != IUCV_BOUND)