[edk2-devel] [PATCH v2 2/2] FatPkg/EnhancedFatDxe: Fix OVERFLOW_BEFORE_WIDEN Coverity issue

["Ranbir Singh" <rsingh@ventanamicro.com>]

From: Ranbir Singh <Ranbir.Singh3@Dell.com>

The function FatInitializeDiskCache evaluates an expression

    FAT_DATACACHE_GROUP_COUNT << DiskCache[CacheData].PageAlignment

and assigns it to DataCacheSize which is of type UINTN.

As per Coverity report,
FAT_DATACACHE_GROUP_COUNT << DiskCache[CacheData].PageAlignment is a
potentially overflowing expression with type "int" (32 bits, signed)
evaluated using 32-bit arithmetic, and then used in a context that
expects an expression of type "UINTN" (64 bits, unsigned).

To avoid overflow, cast "FAT_DATACACHE_GROUP_COUNT" to type "UINTN".

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4249

Cc: Ray Ni <ray.ni@intel.com>
Co-authored-by: Veeresh Sangolli <veeresh.sangolli@dellteam.com>
Signed-off-by: Ranbir Singh <Ranbir.Singh3@Dell.com>
Signed-off-by: Ranbir Singh <rsingh@ventanamicro.com>
---
 FatPkg/EnhancedFatDxe/DiskCache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/FatPkg/EnhancedFatDxe/DiskCache.c b/FatPkg/EnhancedFatDxe/DiskCache.c
index d1a34a6a646f..d56e338586d8 100644
--- a/FatPkg/EnhancedFatDxe/DiskCache.c
+++ b/FatPkg/EnhancedFatDxe/DiskCache.c
@@ -477,7 +477,7 @@ FatInitializeDiskCache (
   DiskCache[CacheFat].BaseAddress   = Volume->FatPos;
   DiskCache[CacheFat].LimitAddress  = Volume->FatPos + Volume->FatSize;
   FatCacheSize                      = FatCacheGroupCount << DiskCache[CacheFat].PageAlignment;
-  DataCacheSize                     = FAT_DATACACHE_GROUP_COUNT << DiskCache[CacheData].PageAlignment;
+  DataCacheSize                     = (UINTN)FAT_DATACACHE_GROUP_COUNT << DiskCache[CacheData].PageAlignment;
   //
   // Allocate the Fat Cache buffer
   //
-- 
2.34.1



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