audk/MdeModulePkg/Universal/Variable
Star Zeng b7dc8888f3 MdeModulePkg Variable: Fix Timestamp zeroing issue on APPEND_WRITE
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=415

When SetVariable() to a time based auth variable with APPEND_WRITE
attribute, and if the EFI_VARIABLE_AUTHENTICATION_2.TimeStamp in
the input Data is earlier than current value, it will cause timestamp
zeroing.

This issue may bring time based auth variable downgrade problem.
For example:
A vendor released three certs at 2014, 2015, and 2016, and system
integrated the 2016 cert. User can SetVariable() with 2015 cert and
APPEND_WRITE attribute to cause timestamp zeroing first, then
SetVariable() with 2014 cert to downgrade the cert.

This patch fixes this issue.

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chao Zhang <chao.b.zhang@intel.com>
Cc: Jian J Wang <jian.j.wang@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>
2018-10-17 11:24:44 +08:00
..
EmuRuntimeDxe MdeModulePkg: Clean up source files 2018-06-28 11:19:45 +08:00
Pei MdeModulePkg Variable: Fix comment typo 'end' to 'start' 2018-09-28 11:13:34 +08:00
RuntimeDxe MdeModulePkg Variable: Fix Timestamp zeroing issue on APPEND_WRITE 2018-10-17 11:24:44 +08:00