[PATCH v2 10/13] vtpmmgr: Remove bogus cast from TPM2_GetRandom

From: Jason Andryuk <jandryuk@gmail.com>
To: xen-devel@lists.xenproject.org
Cc: Jason Andryuk <jandryuk@gmail.com>,
	Daniel De Graaf <dgdegra@tycho.nsa.gov>,
	Quan Xu <quan.xu0@gmail.com>,
	Samuel Thibault <samuel.thibault@ens-lyon.org>
Subject: [PATCH v2 10/13] vtpmmgr: Remove bogus cast from TPM2_GetRandom
Date: Thu,  6 May 2021 09:59:20 -0400	[thread overview]
Message-ID: <20210506135923.161427-11-jandryuk@gmail.com> (raw)
In-Reply-To: <20210506135923.161427-1-jandryuk@gmail.com>

The UINT32 <-> UINT16 casting in TPM2_GetRandom is incorrect.  Use a
local UINT16 as needed for the TPM hardware command and assign the
result.

Suggested-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Jason Andryuk <jandryuk@gmail.com>
---
 stubdom/vtpmmgr/tpm2.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/stubdom/vtpmmgr/tpm2.c b/stubdom/vtpmmgr/tpm2.c
index 655e6d164c..ebd06eac74 100644
--- a/stubdom/vtpmmgr/tpm2.c
+++ b/stubdom/vtpmmgr/tpm2.c
@@ -427,15 +427,22 @@ abort_egress:
 
 TPM_RC TPM2_GetRandom(UINT32 * bytesRequested, BYTE * randomBytes)
 {
+    UINT16 bytesReq;
     TPM_BEGIN(TPM_ST_NO_SESSIONS, TPM_CC_GetRandom);
 
-    ptr = pack_UINT16(ptr, (UINT16)*bytesRequested);
+    if (*bytesRequested > UINT16_MAX)
+        bytesReq = UINT16_MAX;
+    else
+        bytesReq = *bytesRequested;
+
+    ptr = pack_UINT16(ptr, bytesReq);
 
     TPM_TRANSMIT();
     TPM_UNPACK_VERIFY();
 
-    ptr = unpack_UINT16(ptr, (UINT16 *)bytesRequested);
-    ptr = unpack_TPM_BUFFER(ptr, randomBytes, *bytesRequested);
+    ptr = unpack_UINT16(ptr, &bytesReq);
+    *bytesRequested = bytesReq;
+    ptr = unpack_TPM_BUFFER(ptr, randomBytes, bytesReq);
 
 abort_egress:
     return status;
-- 
2.30.2


