[PATCH v3 06/12] MdePkg: Fix conditionally uninitialized variables

["Michael Kubacki" <mikuback@linux.microsoft.com>]

From: Michael Kubacki <michael.kubacki@microsoft.com>

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>
---
 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 98e6d31463e0..637c96e7b31b 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;
 }
 
-- 
2.28.0.windows.1