cifs: prevent possible memory corruption in cifs_demultiplex_thread

cifs_demultiplex_thread sets the addr.sockAddr.sin_port without any
regard for the socket family. While it may be that the error in question
here never occurs on an IPv6 socket, it's probably best to be safe and
set the port properly if it ever does.

Break the port setting code out of cifs_fill_sockaddr and into a new
function, and call that from cifs_demultiplex_thread.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>

1 files changed, 13 insertions, 9 deletions

diff --git a/fs/cifs/netmisc.c b/fs/cifs/netmisc.c
index f97851119e6..9aad47a2d62 100644
--- a/fs/cifs/netmisc.c
+++ b/fs/cifs/netmisc.c
@@ -206,26 +206,30 @@ cifs_convert_address(struct sockaddr *dst, const char *src, int len)
 }
 
 int
-cifs_fill_sockaddr(struct sockaddr *dst, const char *src, int len,
-                   const unsigned short int port)
+cifs_set_port(struct sockaddr *addr, const unsigned short int port)
 {
-        if (!cifs_convert_address(dst, src, len))
-                return 0;
-
-        switch (dst->sa_family) {
+        switch (addr->sa_family) {
         case AF_INET:
-                ((struct sockaddr_in *)dst)->sin_port = htons(port);
+                ((struct sockaddr_in *)addr)->sin_port = htons(port);
                 break;
         case AF_INET6:
-                ((struct sockaddr_in6 *)dst)->sin6_port = htons(port);
+                ((struct sockaddr_in6 *)addr)->sin6_port = htons(port);
                 break;
         default:
                 return 0;
         }
-
         return 1;
 }
 
+int
+cifs_fill_sockaddr(struct sockaddr *dst, const char *src, int len,
+                   const unsigned short int port)
+{
+        if (!cifs_convert_address(dst, src, len))
+                return 0;
+        return cifs_set_port(dst, port);
+}
+
 /*****************************************************************************
 convert a NT status code to a dos class/code
  *****************************************************************************/