CryptoPkg: Fix the pkcs7 get cert fuzz

Signed-off-by: Wenxing Hou <[email protected]>

Author: Wenxing-hou

CryptoPkg/Library/BaseCryptLibMbedTls/Pk/CryptPkcs7VerifyCommon.c

@@ -431,6 +431,8 @@ Pkcs7GetSignedData (
     goto End;
   }
 
+  FreePool (MoreCert);
+
   LastCert = &(SignedData->Certificates);
 
   while(CertNum--) {
@@ -448,8 +450,10 @@ Pkcs7GetSignedData (
     Ret = MbedTlsPkcs7GetSignersInfoSet (&P, End, &SignedData->SignerInfos);
   }
 
+  return Ret;
+
 End:
-  if (MoreCert != NULL) {
+  if ((MoreCert != NULL) && (CertNum !=0)) {
     FreePool (MoreCert);
     MoreCert = NULL;
   }