Limit status message sisze in ts_get_status_check

Thanks to Shi Lei for reporting this issue.
Reviewed-by: NRich Salz <rsalz@openssl.org>

crypto/ts/ts_rsp_verify.c

@@ -451,12 +451,14 @@ static int ts_check_status_info(TS_RESP *response)
 static char *ts_get_status_text(STACK_OF(ASN1_UTF8STRING) *text)
 {
     int i;
-    unsigned int length = 0;
+    int length = 0;
     char *result = NULL;
     char *p;
 
     for (i = 0; i < sk_ASN1_UTF8STRING_num(text); ++i) {
         ASN1_UTF8STRING *current = sk_ASN1_UTF8STRING_value(text, i);
+        if (ASN1_STRING_length(current) > TS_MAX_STATUS_LENGTH - length - 1)
+            return NULL;
         length += ASN1_STRING_length(current);
         length += 1;            /* separator character */
     }

include/openssl/ts.h

@@ -346,6 +346,9 @@ int TS_RESP_CTX_set_clock_precision_digits(TS_RESP_CTX *ctx,
 /* At most we accept usec precision. */
 # define TS_MAX_CLOCK_PRECISION_DIGITS   6
 
+/* Maximum status message length */
+# define TS_MAX_STATUS_LENGTH   (1024 * 1024)
+
 /* No flags are set by default. */
 void TS_RESP_CTX_add_flags(TS_RESP_CTX *ctx, int flags);