Merge lp:~colin-king/ecryptfs/misc-ecryptfs-fixes-dec-2015 into lp:ecryptfs

[Colin Ian King]

Static analysis with Clang's scan-build shows that we can potentially overflow the input buffer if the input is equal or more than the buffer size. Need to guard against this by:

1. Only reading in input_size - 1 chars
2. Checking earlier on to see if input_size is value to insure that we read in at least 1 char

=== modified file 'src/daemon/main.c'
--- src/daemon/main.c	2013-10-25 19:45:09 +0000
+++ src/daemon/main.c	2015-12-16 19:36:41 +0000
@@ -56,7 +56,10 @@
 		memset (input, 0, input_size);
 	}
 
-	if (prompt_prog == NULL) {
+	/*
+	 * Make sure enough buffer size for at least 1 char and EOS
+	 */
+	if ((input_size < 2) || (prompt_prog == NULL)) {
 		rc = -EINVAL;
 		goto out;
 	}
@@ -118,7 +121,7 @@
 	}
 	
 	if (!strcmp (prompt_type, "password")) {
-		if ((r = read (fds[0], input, input_size)) == -1) {
+		if ((r = read (fds[0], input, input_size - 1)) == -1) {
 			rc = -errno;
 			goto out;
 		}