[edk2-devel] [PATCH v2 4/4] MdeModulePkg/Hob: Integer Overflow in CreateHob()

["Guo, Gua" <gua.guo@intel.com>]

From: Gua Guo <gua.guo@intel.com>

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4166

Fix integer overflow in various CreateHob instances.
Fixes: CVE-2022-36765

The CreateHob() function aligns the requested size to 8
performing the following operation:
```
HobLength = (UINT16)((HobLength + 0x7) & (~0x7));
```

No checks are performed to ensure this value doesn't
overflow, and could lead to CreateHob() returning a smaller
HOB than requested, which could lead to OOB HOB accesses.

Reported-by: Marc Beatove <mbeatove@google.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: John Mathew <john.mathews@intel.com>
Authored-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Gua Guo <gua.guo@intel.com>
---
 MdeModulePkg/Core/Pei/Hob/Hob.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdeModulePkg/Core/Pei/Hob/Hob.c b/MdeModulePkg/Core/Pei/Hob/Hob.c
index c4882a23cd..985da50995 100644
--- a/MdeModulePkg/Core/Pei/Hob/Hob.c
+++ b/MdeModulePkg/Core/Pei/Hob/Hob.c
@@ -85,7 +85,7 @@ PeiCreateHob (
   //
   // Check Length to avoid data overflow.
   //
-  if (0x10000 - Length <= 0x7) {
+  if (MAX_UINT16 - Length < 0x7) {
     return EFI_INVALID_PARAMETER;
   }
 
-- 
2.39.2.windows.1



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