smack: off by one error

Consider the input case of a rule that consists entirely of non space
symbols followed by a \0. Say 64 + \0

In this case strlen(data) = 64
kzalloc of subject and object are 64 byte objects
sscanfdata, "%s %s %s", subject, ...)

will put 65 bytes into subject.

Signed-off-by: Alan Cox <alan@linux.intel.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Cc: stable@vger.kernel.org
Signed-off-by: James Morris <james.l.morris@oracle.com>

1 files changed, 4 insertions, 4 deletions

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index d31e6d957c21..b1b768e4049a 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -323,11 +323,11 @@ static int smk_parse_long_rule(const char *data, struct smack_rule *rule,
         int datalen;
         int rc = -1;
 
-        /*
-         * This is probably inefficient, but safe.
-         */
+        /* This is inefficient */
         datalen = strlen(data);
-        subject = kzalloc(datalen, GFP_KERNEL);
+
+        /* Our first element can be 64 + \0 with no spaces */
+        subject = kzalloc(datalen + 1, GFP_KERNEL);
         if (subject == NULL)
                 return -1;
         object = kzalloc(datalen, GFP_KERNEL);