audit: fix potential null dereference 'context->module.name'

The variable 'context->module.name' may be null pointer when
kmalloc return null, so it's better to check it before using
to avoid null dereference.
Another one more thing this patch does is using kstrdup instead
of (kmalloc + strcpy), and signal a lost record via audit_log_lost.

Cc: stable@vger.kernel.org # 4.11
Signed-off-by: Yi Wang <wang.yi59@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
This commit is contained in:
Yi Wang 2018-07-25 10:26:19 +08:00 committed by Paul Moore
parent 5b71388663
commit b305f7ed0f

View File

@ -1279,8 +1279,12 @@ static void show_special(struct audit_context *context, int *call_panic)
break;
case AUDIT_KERN_MODULE:
audit_log_format(ab, "name=");
audit_log_untrustedstring(ab, context->module.name);
kfree(context->module.name);
if (context->module.name) {
audit_log_untrustedstring(ab, context->module.name);
kfree(context->module.name);
} else
audit_log_format(ab, "(null)");
break;
}
audit_log_end(ab);
@ -2411,8 +2415,9 @@ void __audit_log_kern_module(char *name)
{
struct audit_context *context = audit_context();
context->module.name = kmalloc(strlen(name) + 1, GFP_KERNEL);
strcpy(context->module.name, name);
context->module.name = kstrdup(name, GFP_KERNEL);
if (!context->module.name)
audit_log_lost("out of memory in __audit_log_kern_module");
context->type = AUDIT_KERN_MODULE;
}