NFC: Add sockaddr length checks before accessing sa_family in bind handlers

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@google.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/nfc/llcp_sock.c b/net/nfc/llcp_sock.c
index 19c2ca1..e31dea1 100644 (file)
--- a/net/nfc/llcp_sock.c
+++ b/net/nfc/llcp_sock.c
@@ -76,7 +76,8 @@ static int llcp_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
        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 socket *sock, struct sockaddr *addr,
        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);