From: Gua Guo <gua....@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 <mbeat...@google.com>
Cc: Leif Lindholm <quic_llind...@quicinc.com>
Reviewed-by: Ard Biesheuvel <ardb+tianoc...@kernel.org>
Cc: Abner Chang <abner.ch...@amd.com>
Cc: John Mathew <john.math...@intel.com>
Authored-by: Gerd Hoffmann <kra...@redhat.com>
Signed-off-by: Gua Guo <gua....@intel.com>
---
EmbeddedPkg/Library/PrePiHobLib/Hob.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/EmbeddedPkg/Library/PrePiHobLib/Hob.c
b/EmbeddedPkg/Library/PrePiHobLib/Hob.c
index 8eb175aa96..1fe3ea93e4 100644
--- a/EmbeddedPkg/Library/PrePiHobLib/Hob.c
+++ b/EmbeddedPkg/Library/PrePiHobLib/Hob.c
@@ -110,6 +110,13 @@ CreateHob (
HandOffHob = GetHobList ();
+ //
+ // Check Length to avoid data overflow.
+ //
+ if (HobLength > MAX_UINT16 - 0x7) {
+ return NULL;
+ }
+
HobLength = (UINT16)((HobLength + 0x7) & (~0x7));
FreeMemory = HandOffHob->EfiFreeMemoryTop - HandOffHob->EfiFreeMemoryBottom;
--
2.39.2.windows.1
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