Re: [edk2-devel][Patch] MdeModulePkg/DxeCapsuleLibFmp: Add missing NULL pointer check.

["Zhang, Chao B" <chao.b.zhang@intel.com>]

Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>

-----Original Message-----
From: Xu, Wei6 
Sent: Friday, June 28, 2019 12:26 AM
To: devel@edk2.groups.io
Cc: Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>; Zhang, Chao B <chao.b.zhang@intel.com>
Subject: [edk2-devel][Patch] MdeModulePkg/DxeCapsuleLibFmp: Add missing NULL pointer check.

Add missing NULL pointer check for CapsuleNameBufStart.
Also add comments to notice that capsule name integrity check assumes the capsule has been validated by IsValidCapsuleHeader().

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Cc: Chao B Zhang <chao.b.zhang@intel.com>
Signed-off-by: Wei6 Xu <wei6.xu@intel.com>
---
 MdeModulePkg/Library/DxeCapsuleLibFmp/CapsuleOnDisk.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/MdeModulePkg/Library/DxeCapsuleLibFmp/CapsuleOnDisk.c b/MdeModulePkg/Library/DxeCapsuleLibFmp/CapsuleOnDisk.c
index 66c9be8e1f..3193ca8f4d 100644
--- a/MdeModulePkg/Library/DxeCapsuleLibFmp/CapsuleOnDisk.c
+++ b/MdeModulePkg/Library/DxeCapsuleLibFmp/CapsuleOnDisk.c
@@ -23,10 +23,13 @@ IsCapsuleNameCapsule (
 
 /**
   Check the integrity of the capsule name capsule.
   If the capsule is vaild, return the physical address of each capsule name string.
 
+  This routine assumes the capsule has been validated by 
+ IsValidCapsuleHeader(), so  capsule memory overflow is not going to happen in this routine.
+
   @param[in]  CapsuleHeader   Pointer to the capsule header of a capsule name capsule.
   @param[out] CapsuleNameNum  Number of capsule name.
 
   @retval NULL                Capsule name capsule is not valid.
   @retval CapsuleNameBuf      Array of capsule name physical address.
@@ -63,10 +66,13 @@ ValidateCapsuleNameCapsuleIntegrity (
   //
   // If strings are not aligned on a 16-bit boundary, reallocate memory for it.
   //
   if (((UINTN) CapsuleNameBufStart & BIT0) != 0) {
     CapsuleNameBufStart = AllocateCopyPool (CapsuleHeader->CapsuleImageSize - CapsuleHeader->HeaderSize, CapsuleNameBufStart);
+    if (CapsuleNameBufStart == NULL) {
+      return NULL;
+    }
   }
 
   CapsuleNameBufEnd = CapsuleNameBufStart + CapsuleHeader->CapsuleImageSize - CapsuleHeader->HeaderSize;
 
   CapsuleNamePtr = CapsuleNameBufStart;
--
2.16.2.windows.1