ipc: fix potential oops when src msg > 4k w/ MSG_COPY

commit e1082f45 upstream.

If the src msg is > 4k, then dest->next points to the
next allocated segment; resetting it just prior to dereferencing
is bad.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

ipc/msgutil.c

@@ -117,9 +117,6 @@ struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst)
 	if (alen > DATALEN_MSG)
 		alen = DATALEN_MSG;
 
-	dst->next = NULL;
-	dst->security = NULL;
-
 	memcpy(dst + 1, src + 1, alen);
 
 	len -= alen;