SecurityPkg/DxeImageVerificationLib: Check result of GetEfiGlobalVari… #4155
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…able2
Call gRT->GetVariable() directly to read the SecureBoot variable. It is
one byte in size so we can easily place it on the stack instead of
having GetEfiGlobalVariable2() allocate it for us, which avoids a few
possible error cases.
Skip secure boot checks if (and only if):
(a) the SecureBoot variable is not present (EFI_NOT_FOUND) according to
the return value, or
(b) the SecureBoot variable was read successfully and is set to
SECURE_BOOT_MODE_DISABLE.
Previously the code skipped the secure boot checks on *any*
gRT->GetVariable() error (GetEfiGlobalVariable2 sets the variable
value to NULL in that case) and also on memory allocation failures.
Fixes: CVE-2019-14560
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=2167
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Suggested-by: Marvin Häuser <mhaeuser@posteo.de>
Reviewed-by: Min Xu <min.m.xu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
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…able2
Call gRT->GetVariable() directly to read the SecureBoot variable. It is one byte in size so we can easily place it on the stack instead of having GetEfiGlobalVariable2() allocate it for us, which avoids a few possible error cases.
Skip secure boot checks if (and only if):
(a) the SecureBoot variable is not present (EFI_NOT_FOUND) according to
the return value, or
(b) the SecureBoot variable was read successfully and is set to
SECURE_BOOT_MODE_DISABLE.
Previously the code skipped the secure boot checks on any gRT->GetVariable() error (GetEfiGlobalVariable2 sets the variable value to NULL in that case) and also on memory allocation failures.
Fixes: CVE-2019-14560
Bugzilla: https://bugzilla.tianocore.org/show_bug.cgi?id=2167
Suggested-by: Marvin Häuser mhaeuser@posteo.de
Reviewed-by: Min Xu min.m.xu@intel.com
Reviewed-by: Jiewen Yao jiewen.yao@intel.com