smackfs: check for allocation failures in smk_set_access()

smackfs: check for allocation failures in smk_set_access()

 While adding a new subject/object pair to smack_list, smk_set_access()
 didn't check the return of kzalloc().

 This patch changes smk_set_access() to return 0 or -ENOMEM, based on
 kzalloc()'s return. It also updates its caller, smk_write_load(), to
 check for smk_set_access()'s return, given it is no longer a void
 return function.

 Signed-off-by: Sergio Luis <sergio@larces.uece.br>
 To: Casey Schaufler <casey@schaufler-ca.com>
 Cc: Ahmed S. Darwish <darwish.07@gmail.com>
 Cc: LSM <linux-security-module@vger.kernel.org>
 Cc: LKLM <linux-kernel@vger.kernel.org>

Acked-by: Casey Schaufler <casey@schaufler-ca.com>

1 files changed, 16 insertions, 4 deletions

diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
index ca257dfdc75d..247dc9ebbc71 100644
--- a/security/smack/smackfs.c
+++ b/security/smack/smackfs.c
@@ -185,11 +185,15 @@ static int smk_open_load(struct inode *inode, struct file *file)
  * the subject/object pair and replaces the access that was
  * there. If the pair isn't found add it with the specified
  * access.
+ *
+ * Returns 0 if nothing goes wrong or -ENOMEM if it fails
+ * during the allocation of the new pair to add.
  */
-static void smk_set_access(struct smack_rule *srp)
+static int smk_set_access(struct smack_rule *srp)
 {
         struct smk_list_entry *sp;
         struct smk_list_entry *newp;
+        int ret = 0;
 
         mutex_lock(&smack_list_lock);
 
@@ -202,14 +206,20 @@ static void smk_set_access(struct smack_rule *srp)
 
         if (sp == NULL) {
                 newp = kzalloc(sizeof(struct smk_list_entry), GFP_KERNEL);
+                if (newp == NULL) {
+                        ret = -ENOMEM;
+                        goto out;
+                }
+
                 newp->smk_rule = *srp;
                 newp->smk_next = smack_list;
                 smack_list = newp;
         }
 
+out:
         mutex_unlock(&smack_list_lock);
 
-        return;
+        return ret;
 }
 
 /**
@@ -309,8 +319,10 @@ static ssize_t smk_write_load(struct file *file, const char __user *buf,
                 goto out;
         }
 
-        smk_set_access(&rule);
-        rc = count;
+        rc = smk_set_access(&rule);
+
+        if (!rc)
+                rc = count;
 
 out:
         kfree(data);