audk/MdeModulePkg
Hao Wu bd42d976d5 MdeModulePkg/DxeNetLib: Fix negative value left shift
REF: https://bugzilla.tianocore.org/show_bug.cgi?id=698

Within function NetRandomInitSeed(), left shift a negative value is used
in:
"~Time.Hour << 24"

which involves undefined behavior.

Since Time.Hour is of type UINT8 (range from 0 to 23), hence ~Time.Hour
will be a negative value (of type int, signed).

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 will remove the '~' operator before 'Time.Hour', since it
seems like an implementation choice for generating the seed.

Cc: Steven Shi <steven.shi@intel.com>
Cc: Qin Long <qin.long@intel.com>
Cc: Star Zeng <star.zeng@intel.com>
Cc: Eric Dong <eric.dong@intel.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Reviewed-by: Wu Jiaxin <jiaxin.wu@intel.com>
Reviewed-by: Fu Siyuan <siyuan.fu@intel.com>
Reviewed-by: Ye Ting <ting.ye@intel.com>
2017-09-29 16:14:17 +08:00
..
Application MdeModulePkg CapsuleApp: Fix print info in BuildGatherList() 2017-07-03 17:53:16 +08:00
Bus MdeModulePkg/PciBusDxe: Enable Bus Master on P2P bridges on demand 2017-09-28 12:54:53 +08:00
Core MdeModulePkg/Tpl: Fix negative value left shift 2017-09-29 16:14:17 +08:00
Include MdeModulePkg: Add GUID/flags to implement BitField support 2017-09-21 16:17:41 +08:00
Library MdeModulePkg/DxeNetLib: Fix negative value left shift 2017-09-29 16:14:17 +08:00
Logo MdeModulePkg/LogoDxe: Return error if HII Package not present 2017-05-22 16:30:11 -07:00
Universal MdeModulePkg/BdsDxe: Don't delete "BootNext" until booting it 2017-09-29 15:23:15 +08:00
MdeModulePkg.dec MdeModulePkg: Add GUID/flags to implement BitField support 2017-09-21 16:17:41 +08:00
MdeModulePkg.dsc MdeModulePkg: Add UdfDxe to the dsc file 2017-09-13 18:24:40 +08:00
MdeModulePkg.uni MdeModulePkg: Add PROMPT&HELP string of pcd to UNI file 2017-03-07 21:47:19 +08:00
MdeModulePkgExtra.uni MdeModulePkg: Convert all .uni files to utf-8 2015-12-15 04:56:23 +00:00