Hi Gua, Thank you for this patch. Please see my response inline marked [SAMI].
Regards, Sami Mujawar On 11/01/2024, 09:15, "gua....@intel.com <mailto:gua....@intel.com>" <gua....@intel.com <mailto:gua....@intel.com>> wrote: From: Gua Guo <gua....@intel.com <mailto:gua....@intel.com>> REF: https://bugzilla.tianocore.org/show_bug.cgi?id=4166 <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 <mailto:mbeat...@google.com>> Reviewed-by: Ard Biesheuvel <ardb+tianoc...@kernel.org <mailto:ardb+tianoc...@kernel.org>> Cc: Sami Mujawar <sami.muja...@arm.com <mailto:sami.muja...@arm.com>> Cc: Ray Ni <ray...@intel.com <mailto:ray...@intel.com>> Cc: John Mathew <john.math...@intel.com <mailto:john.math...@intel.com>> Authored-by: Gerd Hoffmann <kra...@redhat.com <mailto:kra...@redhat.com>> Signed-off-by: Gua Guo <gua....@intel.com <mailto:gua....@intel.com>> --- .../StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c b/StandaloneMmPkg/Library/StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c index 1550e1babc..bb8426dc0a 100644 --- a/StandaloneMmPkg/Library/StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c +++ b/StandaloneMmPkg/Library/StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c @@ -34,6 +34,13 @@ CreateHob ( HandOffHob = GetHobList (); + // + // Check Length to avoid data overflow. + // + if (HobLength > MAX_UINT16 - 0x7) { + return NULL; [SAMI] Although this fix is correct, I think it shifts the problem somewhere else. If the above condition occurs, a NULL is returned. A quick scan reveals that the calling functions do not check the returned value before use. e.g. https://github.com/tianocore/edk2/blob/master/StandaloneMmPkg/Library/StandaloneMmCoreHobLib/Arm/StandaloneMmCoreHobLib.c#L167-L170 There are multiple such places where the calling functions do not check the pointer returned by CreateHob(). I believe a similar situation can happen for the other patches in this series. [/SAMI] + } + HobLength = (UINT16)((HobLength + 0x7) & (~0x7)); FreeMemory = HandOffHob->EfiFreeMemoryTop - HandOffHob->EfiFreeMemoryBottom; -- 2.39.2.windows.1 -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#113619): https://edk2.groups.io/g/devel/message/113619 Mute This Topic: https://groups.io/mt/103658960/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
