SecurityPkg/DxeImageVerificationLib: reject CertStack.CertNumber==0 per DBX (CVE...
authorJian J Wang <jian.j.wang@intel.com>
Thu, 10 Oct 2019 03:14:47 +0000 (11:14 +0800)
committermergify[bot] <37929162+mergify[bot]@users.noreply.github.com>
Wed, 19 Feb 2020 14:08:23 +0000 (14:08 +0000)
In case the signers' certificate stack, retrieved from the PE/COFF image's
Authenticode blob, has zero elements (=there are zero signer certificates),
then we should consider the image forbidden by DBX, not accepted by DBX.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Signed-off-by: Jian J Wang <jian.j.wang@intel.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c

index 74dbffa..5dcd6ef 100644 (file)
@@ -1326,7 +1326,7 @@ IsForbiddenByDbx (
   //       UINT8  Certn[];\r
   //\r
   Pkcs7GetSigners (AuthData, AuthDataSize, &CertBuffer, &BufferLength, &TrustedCert, &TrustedCertLength);\r
-  if ((BufferLength == 0) || (CertBuffer == NULL)) {\r
+  if ((BufferLength == 0) || (CertBuffer == NULL) || (*CertBuffer) == 0) {\r
     IsForbidden = TRUE;\r
     goto Done;\r
   }\r