useradd: Fix buffer overflow when using a prefix

The buffer length did not count the string's trailing null byte.

Signed-off-by: David Michael <fedora.dm0@gmail.com>

diff --git a/src/useradd.c b/src/useradd.c
index 39a744ee071c818368fe5292391f0a5aca3f9907..7ea0a9c4d87426818f71eae6099a62fff9151ef1 100644 (file)
--- a/src/useradd.c
+++ b/src/useradd.c
@@ -2372,7 +2372,7 @@ static void create_mail (void)
                if (NULL == spool) {
                        return;
                }
-               file = alloca (strlen (prefix) + strlen (spool) + strlen (user_name) + 2);
+               file = alloca (strlen (prefix) + strlen (spool) + strlen (user_name) + 3);
                if (prefix[0])
                        sprintf (file, "%s/%s/%s", prefix, spool, user_name);
                else