audk/SecurityPkg/Library/Tpm2CommandLib
Hao Wu 4333b99d28 SecurityPkg: Refine type cast for pointer subtraction
For pointer subtraction, the result is of type "ptrdiff_t". According to
the C11 standard (Committee Draft - April 12, 2011):

"When two pointers are subtracted, both shall point to elements of the
same array object, or one past the last element of the array object; the
result is the difference of the subscripts of the two array elements. The
size of the result is implementation-defined, and its type (a signed
integer type) is ptrdiff_t defined in the <stddef.h> header. If the result
is not representable in an object of that type, the behavior is
undefined."

In our codes, there are cases that the pointer subtraction is not
performed by pointers to elements of the same array object. This might
lead to potential issues, since the behavior is undefined according to C11
standard.

Also, since the size of type "ptrdiff_t" is implementation-defined. Some
static code checkers may warn that the pointer subtraction might underflow
first and then being cast to a bigger size. For example:

UINT8  *Ptr1, *Ptr2;
UINTN  PtrDiff;
...
PtrDiff = (UINTN) (Ptr1 - Ptr2);

The commit will refine the pointer subtraction expressions by casting each
pointer to UINTN first and then perform the subtraction:

PtrDiff = (UINTN) Ptr1 - (UINTN) Ptr2;

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Hao Wu <hao.a.wu@intel.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Chao Zhang <chao.b.zhang@intel.com>
2017-03-06 14:15:36 +08:00
..
Tpm2Capability.c SecurityPkg: Tcg2Smm: TPM2 Vendor specific HID 2016-12-29 09:45:13 +08:00
Tpm2CommandLib.inf SecurityPkg/TpmCommandLib: Add Tpm2ReadPublic. 2017-02-21 16:47:18 +08:00
Tpm2CommandLib.uni SecurityPkg: Convert all .uni files to utf-8 2015-12-15 04:58:32 +00:00
Tpm2Context.c Add TPM2 commands which might be used in field upgrade. 2014-12-12 04:34:19 +00:00
Tpm2DictionaryAttack.c SecurityPkg: Clear AuthSession content after use. 2016-01-11 05:18:32 +00:00
Tpm2EnhancedAuthorization.c SecurityPkg: Clear AuthSession content after use. 2016-01-11 05:18:32 +00:00
Tpm2Help.c SecurityPkg: Refine type cast for pointer subtraction 2017-03-06 14:15:36 +08:00
Tpm2Hierarchy.c SecurityPkg: Clear AuthSession content after use. 2016-01-11 05:18:32 +00:00
Tpm2Integrity.c SecurityPkg/TPM2: Move Tpm2PcrAllocateBanks() to Tpm2CommandLib 2016-09-21 18:20:16 +08:00
Tpm2Miscellaneous.c SecurityPkg: Clear AuthSession content after use. 2016-01-11 05:18:32 +00:00
Tpm2NVStorage.c SecurityPkg: Correct data copy in Tpm2NvReadPublic. 2016-01-27 12:16:47 +00:00
Tpm2Object.c SecurityPkg/TpmCommandLib: Add Tpm2ReadPublic. 2017-02-21 16:47:18 +08:00
Tpm2Sequences.c Add TPM2 implementation. 2013-09-18 05:31:18 +00:00
Tpm2Session.c Use better coding style. 2014-12-19 05:21:55 +00:00
Tpm2Startup.c SecurityPkg: Add DEBUG messages for TPM2Startup 2016-05-03 10:03:41 +08:00
Tpm2Test.c Add TPM2 implementation. 2013-09-18 05:31:18 +00:00