From 321240b135e37ac1b9be1317f78ce2a3b526bf02 Mon Sep 17 00:00:00 2001
From: Michael Kubacki <michael.kubacki@microsoft.com>
Date: Tue, 8 Nov 2022 15:29:05 -0500
Subject: [PATCH] MdePkg: Fix conditionally uninitialized variables

Fixes CodeQL alerts for CWE-457:
https://cwe.mitre.org/data/definitions/457.html

Note that this change affects the actual return value from the
following functions. The functions documented that if an integer
overflow occurred, MAX_UINTN would be returned. They were
implemented to actually return an undefined value from the stack.

This change makes the function follow its description. However, this
is technically different than what callers may have previously
expected.

MdePkg/Library/BaseLib/String.c:
  - StrDecimalToUintn()
  - StrDecimalToUint64()
  - StrHexToUintn()
  - StrHexToUint64()
  - AsciiStrDecimalToUintn()
  - AsciiStrDecimalToUint64()
  - AsciiStrHexToUintn()
  - AsciiStrHexToUint64()

Cc: Erich McMillan <emcmillan@microsoft.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Michael Kubacki <mikuback@linux.microsoft.com>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>
Co-authored-by: Erich McMillan <emcmillan@microsoft.com>
Signed-off-by: Michael Kubacki <michael.kubacki@microsoft.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
Reviewed-by: Oliver Smith-Denny <osd@smith-denny.com>
---
 MdePkg/Library/BaseLib/String.c | 40 ++++++++++++++++++++++++++-------
 1 file changed, 32 insertions(+), 8 deletions(-)

diff --git a/MdePkg/Library/BaseLib/String.c b/MdePkg/Library/BaseLib/String.c
index 98e6d31463..637c96e7b3 100644
--- a/MdePkg/Library/BaseLib/String.c
+++ b/MdePkg/Library/BaseLib/String.c
@@ -408,7 +408,10 @@ StrDecimalToUintn (
 {
   UINTN  Result;
 
-  StrDecimalToUintnS (String, (CHAR16 **)NULL, &Result);
+  if (RETURN_ERROR (StrDecimalToUintnS (String, (CHAR16 **)NULL, &Result))) {
+    return MAX_UINTN;
+  }
+
   return Result;
 }
 
@@ -454,7 +457,10 @@ StrDecimalToUint64 (
 {
   UINT64  Result;
 
-  StrDecimalToUint64S (String, (CHAR16 **)NULL, &Result);
+  if (RETURN_ERROR (StrDecimalToUint64S (String, (CHAR16 **)NULL, &Result))) {
+    return MAX_UINT64;
+  }
+
   return Result;
 }
 
@@ -501,7 +507,10 @@ StrHexToUintn (
 {
   UINTN  Result;
 
-  StrHexToUintnS (String, (CHAR16 **)NULL, &Result);
+  if (RETURN_ERROR (StrHexToUintnS (String, (CHAR16 **)NULL, &Result))) {
+    return MAX_UINTN;
+  }
+
   return Result;
 }
 
@@ -548,7 +557,10 @@ StrHexToUint64 (
 {
   UINT64  Result;
 
-  StrHexToUint64S (String, (CHAR16 **)NULL, &Result);
+  if (RETURN_ERROR (StrHexToUint64S (String, (CHAR16 **)NULL, &Result))) {
+    return MAX_UINT64;
+  }
+
   return Result;
 }
 
@@ -989,7 +1001,10 @@ AsciiStrDecimalToUintn (
 {
   UINTN  Result;
 
-  AsciiStrDecimalToUintnS (String, (CHAR8 **)NULL, &Result);
+  if (RETURN_ERROR (AsciiStrDecimalToUintnS (String, (CHAR8 **)NULL, &Result))) {
+    return MAX_UINTN;
+  }
+
   return Result;
 }
 
@@ -1031,7 +1046,10 @@ AsciiStrDecimalToUint64 (
 {
   UINT64  Result;
 
-  AsciiStrDecimalToUint64S (String, (CHAR8 **)NULL, &Result);
+  if (RETURN_ERROR (AsciiStrDecimalToUint64S (String, (CHAR8 **)NULL, &Result))) {
+    return MAX_UINT64;
+  }
+
   return Result;
 }
 
@@ -1077,7 +1095,10 @@ AsciiStrHexToUintn (
 {
   UINTN  Result;
 
-  AsciiStrHexToUintnS (String, (CHAR8 **)NULL, &Result);
+  if (RETURN_ERROR (AsciiStrHexToUintnS (String, (CHAR8 **)NULL, &Result))) {
+    return MAX_UINTN;
+  }
+
   return Result;
 }
 
@@ -1123,7 +1144,10 @@ AsciiStrHexToUint64 (
 {
   UINT64  Result;
 
-  AsciiStrHexToUint64S (String, (CHAR8 **)NULL, &Result);
+  if (RETURN_ERROR (AsciiStrHexToUint64S (String, (CHAR8 **)NULL, &Result))) {
+    return MAX_UINT64;
+  }
+
   return Result;
 }