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SecurityPkg/DxeImageVerificationHandler: fix imgexec info on memalloc fail 

It makes no sense to call AddImageExeInfo() with (Signature == NULL) and
(SignatureSize > 0). AddImageExeInfo() does not crash in such a case -- it
avoids the CopyMem() call --, but it creates an invalid
EFI_IMAGE_EXECUTION_INFO record. Namely, the
"EFI_IMAGE_EXECUTION_INFO.InfoSize" field includes "SignatureSize", but
the actual signature bytes are not filled in.

Document and ASSERT() this condition in AddImageExeInfo().

In DxeImageVerificationHandler(), zero out "SignatureListSize" if we set
"SignatureList" to NULL due to AllocateZeroPool() failure.

(Another approach could be to avoid calling AddImageExeInfo() completely,
in case AllocateZeroPool() fails. Unfortunately, the UEFI v2.8 spec does
not seem to state clearly whether a signature is mandatory in
EFI_IMAGE_EXECUTION_INFO, if the "Action" field is
EFI_IMAGE_EXECUTION_AUTH_SIG_FAILED or EFI_IMAGE_EXECUTION_AUTH_SIG_FOUND.

For now, the EFI_IMAGE_EXECUTION_INFO addition logic is not changed; we
only make sure that the record we add is not malformed.)

Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2129
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200116190705.18816-11-lersek@redhat.com>
Reviewed-by: Michael D Kinney <michael.d.kinney@intel.com>
[lersek@redhat.com: push with Mike's R-b due to Chinese New Year
 Holiday: <https://edk2.groups.io/g/devel/message/53429>; msgid
 <d3fbb76dabed4e1987c512c328c82810@intel.com>]
This commit is contained in:
Laszlo Ersek 2020-01-16 14:19:58 +01:00 committed by mergify[bot]
parent 6d57592740
commit 6aa31db5eb
1 changed files with 3 additions and 1 deletions
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4
SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
View File

@ -704,7 +704,7 @@ GetImageExeInfoTableSize (
@param[in] Name Input a null-terminated, user-friendly name.
@param[in] DevicePath Input device path pointer.
@param[in] Signature Input signature info in EFI_SIGNATURE_LIST data structure.
@param[in] SignatureSize Size of signature.
@param[in] SignatureSize Size of signature. Must be zero if Signature is NULL.
**/
VOID
@ -761,6 +761,7 @@ AddImageExeInfo (
//
// Signature size can be odd. Pad after signature to ensure next EXECUTION_INFO entry align
//
ASSERT (Signature != NULL || SignatureSize == 0);
NewImageExeInfoEntrySize = sizeof (EFI_IMAGE_EXECUTION_INFO) + NameStringLen + DevicePathSize + SignatureSize;
NewImageExeInfoTable = (EFI_IMAGE_EXECUTION_INFO_TABLE *) AllocateRuntimePool (ImageExeInfoTableSize + NewImageExeInfoEntrySize);
@ -1858,6 +1859,7 @@ DxeImageVerificationHandler (
SignatureListSize = sizeof (EFI_SIGNATURE_LIST) + sizeof (EFI_SIGNATURE_DATA) - 1 + mImageDigestSize;
SignatureList = (EFI_SIGNATURE_LIST *) AllocateZeroPool (SignatureListSize);
if (SignatureList == NULL) {
SignatureListSize = 0;
goto Failed;
}
SignatureList->SignatureHeaderSize = 0;