audit: catch possible NULL audit buffers
It's possible for audit_log_start() to return NULL. Handle it in the
various callers.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Eric Paris <eparis@redhat.com>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Julien Tinnes <jln@google.com>
Cc: Will Drewry <wad@google.com>
Cc: Steve Grubb <sgrubb@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c
index e81175e..642a89c 100644
--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -449,11 +449,26 @@
return 0;
}
+static void audit_log_remove_rule(struct audit_krule *rule)
+{
+ struct audit_buffer *ab;
+
+ ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
+ if (unlikely(!ab))
+ return;
+ audit_log_format(ab, "op=");
+ audit_log_string(ab, "remove rule");
+ audit_log_format(ab, " dir=");
+ audit_log_untrustedstring(ab, rule->tree->pathname);
+ audit_log_key(ab, rule->filterkey);
+ audit_log_format(ab, " list=%d res=1", rule->listnr);
+ audit_log_end(ab);
+}
+
static void kill_rules(struct audit_tree *tree)
{
struct audit_krule *rule, *next;
struct audit_entry *entry;
- struct audit_buffer *ab;
list_for_each_entry_safe(rule, next, &tree->rules, rlist) {
entry = container_of(rule, struct audit_entry, rule);
@@ -461,14 +476,7 @@
list_del_init(&rule->rlist);
if (rule->tree) {
/* not a half-baked one */
- ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_CONFIG_CHANGE);
- audit_log_format(ab, "op=");
- audit_log_string(ab, "remove rule");
- audit_log_format(ab, " dir=");
- audit_log_untrustedstring(ab, rule->tree->pathname);
- audit_log_key(ab, rule->filterkey);
- audit_log_format(ab, " list=%d res=1", rule->listnr);
- audit_log_end(ab);
+ audit_log_remove_rule(rule);
rule->tree = NULL;
list_del_rcu(&entry->list);
list_del(&entry->rule.list);
