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SecurityPkg/DxeImageVerificationLib: catch alignment overflow (CVE-2019-14562) 

The DxeImageVerificationHandler() function currently checks whether
"SecDataDir" has enough room for "WinCertificate->dwLength". However, for
advancing "OffSet", "WinCertificate->dwLength" is aligned to the next
multiple of 8. If "WinCertificate->dwLength" is large enough, the
alignment will return 0, and "OffSet" will be stuck at the same value.

Check whether "SecDataDir" has room left for both
"WinCertificate->dwLength" and the alignment.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Min Xu <min.m.xu@intel.com>
Cc: Wenyi Xie <xiewenyi2@huawei.com>
Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2215
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20200901091221.20948-4-lersek@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Tested-by: Wenyi Xie <xiewenyi2@huawei.com>
Reviewed-by: Min M Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
This commit is contained in:
Laszlo Ersek 2020-09-01 11:12:21 +02:00 committed by mergify[bot]
parent a7632e913c
commit 0b143fa43e
1 changed files with 3 additions and 1 deletions
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4
SecurityPkg/Library/DxeImageVerificationLib/DxeImageVerificationLib.c
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@ -1860,7 +1860,9 @@ DxeImageVerificationHandler (
break;
}
WinCertificate = (WIN_CERTIFICATE *) (mImageBase + OffSet);
if (SecDataDirLeft < WinCertificate->dwLength) {
if (SecDataDirLeft < WinCertificate->dwLength ||
(SecDataDirLeft - WinCertificate->dwLength <
ALIGN_SIZE (WinCertificate->dwLength))) {
break;
}