linux-kernel - [PATCH 4.9 006/172] af_unix: Add sockaddr length checks before accessing sa

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Message-Id: <20170703133414.565463868@linuxfoundation.org>
Date:   Mon,  3 Jul 2017 15:33:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Mateusz Jurczyk <mjurczyk@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.9 006/172] af_unix: Add sockaddr length checks before accessing sa_family in bind and connect handlers

4.9-stable review patch.  If anyone has any objections, please let me know.

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

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


[ Upstream commit defbcf2decc903a28d8398aa477b6881e711e3ea ]

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_UNIX 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.

Signed-off-by: Mateusz Jurczyk <mjurczyk@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/unix/af_unix.c |    7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -998,7 +998,8 @@ static int unix_bind(struct socket *sock
 	struct path path = { NULL, NULL };
 
 	err = -EINVAL;
-	if (sunaddr->sun_family != AF_UNIX)
+	if (addr_len < offsetofend(struct sockaddr_un, sun_family) ||
+	    sunaddr->sun_family != AF_UNIX)
 		goto out;
 
 	if (addr_len == sizeof(short)) {
@@ -1109,6 +1110,10 @@ static int unix_dgram_connect(struct soc
 	unsigned int hash;
 	int err;
 
+	err = -EINVAL;
+	if (alen < offsetofend(struct sockaddr, sa_family))
+		goto out;
+
 	if (addr->sa_family != AF_UNSPEC) {
 		err = unix_mkname(sunaddr, alen, &hash);
 		if (err < 0)