linux-kernel - [PATCH 4.4 14/83] NFC: Add sockaddr length checks before accessing sa

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Message-Id: <20170725191710.585129830@linuxfoundation.org>
Date:   Tue, 25 Jul 2017 12:18:38 -0700
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>,
        Samuel Ortiz <sameo@...ux.intel.com>
Subject: [PATCH 4.4 14/83] NFC: Add sockaddr length checks before accessing sa_family in bind handlers

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

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

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

commit f6a5885fc4d68e7f25ffb42b9d8d80aebb3bacbb upstream.

Verify that the caller-provided sockaddr structure is large enough to
contain the sa_family field, before accessing it in bind() handlers of the
AF_NFC socket. Since the syscall doesn't enforce 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: Samuel Ortiz <sameo@...ux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 net/nfc/llcp_sock.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -76,7 +76,8 @@ static int llcp_sock_bind(struct socket
 	struct sockaddr_nfc_llcp llcp_addr;
 	int len, ret = 0;
 
-	if (!addr || addr->sa_family != AF_NFC)
+	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+	    addr->sa_family != AF_NFC)
 		return -EINVAL;
 
 	pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);
@@ -150,7 +151,8 @@ static int llcp_raw_sock_bind(struct soc
 	struct sockaddr_nfc_llcp llcp_addr;
 	int len, ret = 0;
 
-	if (!addr || addr->sa_family != AF_NFC)
+	if (!addr || alen < offsetofend(struct sockaddr, sa_family) ||
+	    addr->sa_family != AF_NFC)
 		return -EINVAL;
 
 	pr_debug("sk %p addr %p family %d\n", sk, addr, addr->sa_family);