selinux: check sidtab limit before adding a new entry

We need to error out when trying to add an entry above SIDTAB_MAX in sidtab_reverse_lookup() to avoid overflow on the odd chance that this happens. Cc: [email protected] Fixes: ee1a84f ("selinux: overhaul sidtab to fix bug and improve performance") Signed-off-by: Ondrej Mosnacek <[email protected]> Reviewed-by: Kees Cook <[email protected]> Signed-off-by: Paul Moore <[email protected]>
jbg · Jul 24, 2019 · acbc372 · acbc372
1 parent ea74a68
commit acbc372
Showing 1 changed file with 5 additions and 0 deletions.
diff --git a/security/selinux/ss/sidtab.c b/security/selinux/ss/sidtab.c
@@ -286,6 +286,11 @@ static int sidtab_reverse_lookup(struct sidtab *s, struct context *context,
 		++count;
 	}
 
+	/* bail out if we already reached max entries */
+	rc = -EOVERFLOW;
+	if (count >= SIDTAB_MAX)
+		goto out_unlock;
+
 	/* insert context into new entry */
 	rc = -ENOMEM;
 	dst = sidtab_do_lookup(s, count, 1);