[PATCH] IntelFrameworkModulePkg/DebugLib: Fix string copy issue

["Gao, Zhichao" <zhichao.gao@intel.com>]

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=1826

There is a bug to use AsciiStrCpyS to copy a truncated
string. If would cause an assert because the truncated
length is always less than the source string length. It
should use the AsciiStrnCpyS instead.

Cc: Liming Gao <liming.gao@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Zhichao Gao <zhichao.gao@intel.com>
---
 .../Library/PeiDxeDebugLibReportStatusCode/DebugLib.c         | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/IntelFrameworkModulePkg/Library/PeiDxeDebugLibReportStatusCode/DebugLib.c b/IntelFrameworkModulePkg/Library/PeiDxeDebugLibReportStatusCode/DebugLib.c
index e92601f89e..1840b6d683 100644
--- a/IntelFrameworkModulePkg/Library/PeiDxeDebugLibReportStatusCode/DebugLib.c
+++ b/IntelFrameworkModulePkg/Library/PeiDxeDebugLibReportStatusCode/DebugLib.c
@@ -150,7 +150,7 @@ DebugPrintMarker (
   FormatString          = (CHAR8 *)((UINT64 *)(DebugInfo + 1) + 12);
 
   //
-  // Copy the Format string into the record
+  // Copy the Format string into the record. It will be truncated if it's too long.
   //
   // According to the content structure of Buffer shown above, the size of
   // the FormatString buffer is the size of Buffer minus the Padding
@@ -158,7 +158,7 @@ DebugPrintMarker (
   // variable arguments (12 * sizeof (UINT64)).
   //
   DestBufferSize = sizeof (Buffer) - 4 - sizeof (EFI_DEBUG_INFO) - 12 * sizeof (UINT64);
-  AsciiStrCpyS (FormatString, DestBufferSize / sizeof (CHAR8), Format);
+  AsciiStrnCpyS (FormatString, DestBufferSize / sizeof (CHAR8), Format, DestBufferSize / sizeof (CHAR8) - 1);
 
   //
   // The first 12 * sizeof (UINT64) bytes following EFI_DEBUG_INFO are for variable arguments
-- 
2.21.0.windows.1