Re: [edk2-devel] [PATCH] IntelFsp2Pkg/Library/BaseFspCommonLib: Fix OVERRUN Coverity issue

["Ranbir Singh" <Ranbir.Singh3@Dell.com>]

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Copying patch contents directly in the message below ...

>From e0df5b0a34f1b96aa9610c5eef9161cbbca717d2 Mon Sep 17 00:00:00 2001
From: Ranbir Singh <Ranbir.Singh3@Dell.com>
Date: Thu, 22 Dec 2022 10:57:21 +0530
Subject: [PATCH] IntelFsp2Pkg/Library/BaseFspCommonLib: Fix OVERRUN Coverity
issue

FspData->PerfIdx is getting increased for every call unconditionally
in the function SetFspMeasurePoint and hence memory access can happen
for out of bound FspData->PerfData[] array entries also.

Example -
FspData->PerfData is an array of 32 UINT64 entries. Assume a call
is made to SetFspMeasurePoint function when the FspData->PerfIdx
last value is 31. It gets incremented to 32 at line 400.
Any subsequent call to SetFspMeasurePoint functions leads to
FspData->PerfData[32] getting accessed which is out of the PerfData
array as well as the FSP_GLOBAL_DATA structure boundary.

Hence keep array access and index increment inside if block only and
return invalid performance timestamp when PerfIdx is invalid.

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4200
Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
---
IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
index a22b0e7825..cda2a7b247 100644
--- a/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
+++ b/IntelFsp2Pkg/Library/BaseFspCommonLib/FspCommonLib.c
@@ -377,7 +377,8 @@ GetFspSiliconInitUpdDataPointer (

@param[in] Id       Measurement point ID.

-  @return performance timestamp.
+  @return performance timestamp if current PerfIdx is valid,
+          else return 0 as invalid performance timestamp
**/
UINT64
EFIAPI
@@ -395,9 +396,10 @@ SetFspMeasurePoint (
if (FspData->PerfIdx < sizeof (FspData->PerfData) / sizeof (FspData->PerfData[0])) {
FspData->PerfData[FspData->PerfIdx]                  = AsmReadTsc ();
((UINT8 *)(&FspData->PerfData[FspData->PerfIdx]))[7] = Id;
+    return FspData->PerfData[(FspData->PerfIdx)++];
}

-  return FspData->PerfData[(FspData->PerfIdx)++];
+  return (UINT64)0x0000000000000000;
}

/**
--
2.36.1.windows.1

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