Integrity: Pass commname via get_task_comm()

When we pass task->comm to audit_log_untrustedstring(), we need to pass it
via get_task_comm() because task->comm can be changed to contain untrusted
string by other threads after audit_log_untrustedstring() confirmed that
task->comm does not contain untrusted string.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

security/integrity/integrity_audit.c

@@ -33,6 +33,7 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
 			 const char *cause, int result, int audit_info)
 {
 	struct audit_buffer *ab;
+	char name[TASK_COMM_LEN];
 
 	if (!integrity_audit_info && audit_info == 1)	/* Skip info messages */
 		return;
@@ -49,7 +50,7 @@ void integrity_audit_msg(int audit_msgno, struct inode *inode,
 	audit_log_format(ab, " cause=");
 	audit_log_string(ab, cause);
 	audit_log_format(ab, " comm=");
-	audit_log_untrustedstring(ab, current->comm);
+	audit_log_untrustedstring(ab, get_task_comm(name, current));
 	if (fname) {
 		audit_log_format(ab, " name=");
 		audit_log_untrustedstring(ab, fname);