audk/MdePkg
Hao Wu ea0b15067c MdePkg/PrintLib: Fix possible negative value left shift
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=702

Within function InternalPrintLibSPrintMarker(), possible left shift of a
negative value is found in:
"(*(ArgumentString + 1) << 8)"

which involves undefined behavior.

Since '*(ArgumentString + 1)' is of type CONST CHAR8 (signed), it will be
promoted to type int (signed) during the left shift operation. If
'*(ArgumentString + 1)' is a negative value, the behavior will be
undefined.

According to the C11 spec, Section 6.5.7:
> 4 The result of E1 << E2 is E1 left-shifted E2 bit positions; vacated
>   bits are filled with zeros. If E1 has an unsigned type, the value
>   of the result is E1 * 2^E2 , reduced modulo one more than the
>   maximum value representable in the result type. If E1 has a signed
>   type and nonnegative value, and E1 * 2^E2 is representable in the
>   result type, then that is the resulting value; otherwise, the
>   behavior is undefined.

This commit explicitly cast '*(ArgumentString + 1)' with UINT8 to resolve
this issue.

Cc: Steven Shi <steven.shi@intel.com>
Cc: Michael Kinney <michael.d.kinney@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2017-09-29 16:14:17 +08:00
..
Include MdePkg/Http.h: Clarify the usage of HttpConfigData in HTTP protocol 2017-09-29 09:01:52 +08:00
Library MdePkg/PrintLib: Fix possible negative value left shift 2017-09-29 16:14:17 +08:00
MdePkg.dec MdePkg: Add new definitions for Management Mode. 2017-08-29 09:37:36 +08:00
MdePkg.dsc MdePkg/S3PciSegmentLib: Add S3PciSegmentLib class and instance. 2017-08-28 16:47:05 +08:00
MdePkg.uni MdePkg/MdePkg.uni: Add description for PcdUartDefaultReceiveFifoDepth 2016-04-05 14:09:32 +08:00
MdePkgExtra.uni MdePkg: Convert all .uni files to utf-8 2015-12-15 04:53:50 +00:00