MdePkg/BaseSafeIntLib: Add SafeIntLib class and instance
https://bugzilla.tianocore.org/show_bug.cgi?id=798
SafeIntLib provides helper functions to prevent integer overflow
during type conversion, addition, subtraction, and multiplication.
Conversion Functions
====================
* Converting from a signed type to an unsigned type of the same
size, or vice-versa.
* Converting to a smaller type that could possibly overflow.
* Converting from a signed type to a larger unsigned type.
Unsigned Addition, Subtraction, Multiplication
===============================================
* Unsigned integer math functions protect from overflow and
underflow (in case of subtraction).
Signed Addition, Subtraction, Multiplication
============================================
* Strongly consider using unsigned numbers.
* Signed numbers are often used where unsigned numbers should
be used. For example file sizes and array indices should always
be unsigned. Subtracting a larger positive signed number from a
smaller positive signed number with SafeInt32Sub() will succeed,
producing a negative number, that then must not be used as an
array index (but can occasionally be used as a pointer index.)
Similarly for adding a larger magnitude negative number to a
smaller magnitude positive number.
* SafeIntLib does not protect you from such errors. It tells you
if your integer operations overflowed, not if you are doing the
right thing with your non-overflowed integers.
* Likewise you can overflow a buffer with a non-overflowed
unsigned index.
Based on content from the following branch/commits:
https://github.com/Microsoft/MS_UEFI/tree/share/MsCapsuleSupport
https://github.com/Microsoft/MS_UEFI/commit/21ef3a321c907b40fa93797619c9f6c686dd92e0
https://github.com/Microsoft/MS_UEFI/commit/ca516b1a61315c2d823f453e12d2135098f53d61
https://github.com/Microsoft/MS_UEFI/commit/33bab4031a417d7d5a7d356c15a14c2e60302b2d
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2017-04-25 01:37:20 +02:00
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/** @file
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This library provides helper functions to prevent integer overflow during
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type conversion, addition, subtraction, and multiplication.
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Copyright (c) 2017, Microsoft Corporation
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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1. Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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2. Redistributions in binary form must reproduce the above copyright notice,
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this list of conditions and the following disclaimer in the documentation
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and/or other materials provided with the distribution.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
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ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
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OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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**/
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#include <Base.h>
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#include <Library/SafeIntLib.h>
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2018-02-26 04:55:15 +01:00
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#include <Library/BaseLib.h>
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MdePkg/BaseSafeIntLib: Add SafeIntLib class and instance
https://bugzilla.tianocore.org/show_bug.cgi?id=798
SafeIntLib provides helper functions to prevent integer overflow
during type conversion, addition, subtraction, and multiplication.
Conversion Functions
====================
* Converting from a signed type to an unsigned type of the same
size, or vice-versa.
* Converting to a smaller type that could possibly overflow.
* Converting from a signed type to a larger unsigned type.
Unsigned Addition, Subtraction, Multiplication
===============================================
* Unsigned integer math functions protect from overflow and
underflow (in case of subtraction).
Signed Addition, Subtraction, Multiplication
============================================
* Strongly consider using unsigned numbers.
* Signed numbers are often used where unsigned numbers should
be used. For example file sizes and array indices should always
be unsigned. Subtracting a larger positive signed number from a
smaller positive signed number with SafeInt32Sub() will succeed,
producing a negative number, that then must not be used as an
array index (but can occasionally be used as a pointer index.)
Similarly for adding a larger magnitude negative number to a
smaller magnitude positive number.
* SafeIntLib does not protect you from such errors. It tells you
if your integer operations overflowed, not if you are doing the
right thing with your non-overflowed integers.
* Likewise you can overflow a buffer with a non-overflowed
unsigned index.
Based on content from the following branch/commits:
https://github.com/Microsoft/MS_UEFI/tree/share/MsCapsuleSupport
https://github.com/Microsoft/MS_UEFI/commit/21ef3a321c907b40fa93797619c9f6c686dd92e0
https://github.com/Microsoft/MS_UEFI/commit/ca516b1a61315c2d823f453e12d2135098f53d61
https://github.com/Microsoft/MS_UEFI/commit/33bab4031a417d7d5a7d356c15a14c2e60302b2d
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2017-04-25 01:37:20 +02:00
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/**
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INT32 -> UINTN conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeInt32ToUintn (
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IN INT32 Operand,
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OUT UINTN *Result
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)
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{
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return SafeInt32ToUint32 (Operand, (UINT32 *)Result);
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}
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/**
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UINT32 -> INTN conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeUint32ToIntn (
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IN UINT32 Operand,
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OUT INTN *Result
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)
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{
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return SafeUint32ToInt32 (Operand, (INT32 *)Result);
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}
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/**
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INTN -> INT32 conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to INT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeIntnToInt32 (
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IN INTN Operand,
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OUT INT32 *Result
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)
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{
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if (Result == NULL) {
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return RETURN_INVALID_PARAMETER;
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}
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*Result = (INT32)Operand;
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return RETURN_SUCCESS;
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}
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/**
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INTN -> UINT32 conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to UINT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeIntnToUint32 (
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IN INTN Operand,
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OUT UINT32 *Result
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)
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{
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RETURN_STATUS Status;
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if (Result == NULL) {
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return RETURN_INVALID_PARAMETER;
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}
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if (Operand >= 0) {
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*Result = (UINT32)Operand;
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Status = RETURN_SUCCESS;
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} else {
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*Result = UINT32_ERROR;
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Status = RETURN_BUFFER_TOO_SMALL;
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}
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return Status;
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}
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/**
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UINTN -> UINT32 conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to UINT32_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeUintnToUint32 (
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IN UINTN Operand,
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OUT UINT32 *Result
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)
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{
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if (Result == NULL) {
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return RETURN_INVALID_PARAMETER;
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}
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*Result = (UINT32)Operand;
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return RETURN_SUCCESS;
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}
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/**
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UINTN -> INT64 conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to INT64_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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EFIAPI
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SafeUintnToInt64 (
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IN UINTN Operand,
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OUT INT64 *Result
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)
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{
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if (Result == NULL) {
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return RETURN_INVALID_PARAMETER;
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}
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*Result = (INT64)Operand;
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return RETURN_SUCCESS;
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}
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/**
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INT64 -> INTN conversion
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Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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If the conversion results in an overflow or an underflow condition, then
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Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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@param[in] Operand Operand to be converted to new type
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@param[out] Result Pointer to the result of conversion
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@retval RETURN_SUCCESS Successful conversion
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@retval RETURN_BUFFER_TOO_SMALL Overflow
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@retval RETURN_INVALID_PARAMETER Result is NULL
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**/
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RETURN_STATUS
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|
EFIAPI
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SafeInt64ToIntn (
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IN INT64 Operand,
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OUT INTN *Result
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)
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{
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return SafeInt64ToInt32 (Operand, (INT32 *)Result);
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}
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/**
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INT64 -> UINTN conversion
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|
Converts the value specified by Operand to a value specified by Result type
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and stores the converted value into the caller allocated output buffer
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specified by Result. The caller must pass in a Result buffer that is at
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least as large as the Result type.
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|
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If Result is NULL, RETURN_INVALID_PARAMETER is returned.
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|
If the conversion results in an overflow or an underflow condition, then
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|
Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
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|
@param[in] Operand Operand to be converted to new type
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|
|
@param[out] Result Pointer to the result of conversion
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful conversion
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeInt64ToUintn (
|
|
|
|
|
IN INT64 Operand,
|
|
|
|
|
OUT UINTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
return SafeInt64ToUint32 (Operand, (UINT32 *)Result);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
UINT64 -> UINTN conversion
|
|
|
|
|
|
|
|
|
|
Converts the value specified by Operand to a value specified by Result type
|
|
|
|
|
and stores the converted value into the caller allocated output buffer
|
|
|
|
|
specified by Result. The caller must pass in a Result buffer that is at
|
|
|
|
|
least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the conversion results in an overflow or an underflow condition, then
|
|
|
|
|
Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Operand Operand to be converted to new type
|
|
|
|
|
@param[out] Result Pointer to the result of conversion
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful conversion
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeUint64ToUintn (
|
|
|
|
|
IN UINT64 Operand,
|
|
|
|
|
OUT UINTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
return SafeUint64ToUint32 ((UINT64) Operand, (UINT32 *)Result);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
UINTN addition
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Augend A number to which addend will be added
|
|
|
|
|
@param[in] Addend A number to be added to another
|
|
|
|
|
@param[out] Result Pointer to the result of addition
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful addition
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeUintnAdd (
|
|
|
|
|
IN UINTN Augend,
|
|
|
|
|
IN UINTN Addend,
|
|
|
|
|
OUT UINTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
RETURN_STATUS Status;
|
|
|
|
|
|
|
|
|
|
if (Result == NULL) {
|
|
|
|
|
return RETURN_INVALID_PARAMETER;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if ((Augend + Addend) >= Augend) {
|
|
|
|
|
*Result = (Augend + Addend);
|
|
|
|
|
Status = RETURN_SUCCESS;
|
|
|
|
|
} else {
|
|
|
|
|
*Result = UINTN_ERROR;
|
|
|
|
|
Status = RETURN_BUFFER_TOO_SMALL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return Status;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
UINTN subtraction
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Minuend A number from which another is to be subtracted.
|
|
|
|
|
@param[in] Subtrahend A number to be subtracted from another
|
|
|
|
|
@param[out] Result Pointer to the result of subtraction
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful subtraction
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Underflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeUintnSub (
|
|
|
|
|
IN UINTN Minuend,
|
|
|
|
|
IN UINTN Subtrahend,
|
|
|
|
|
OUT UINTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
RETURN_STATUS Status;
|
|
|
|
|
|
|
|
|
|
if (Result == NULL) {
|
|
|
|
|
return RETURN_INVALID_PARAMETER;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
if (Minuend >= Subtrahend) {
|
|
|
|
|
*Result = (Minuend - Subtrahend);
|
|
|
|
|
Status = RETURN_SUCCESS;
|
|
|
|
|
} else {
|
|
|
|
|
*Result = UINTN_ERROR;
|
|
|
|
|
Status = RETURN_BUFFER_TOO_SMALL;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
return Status;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
UINTN multiplication
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to UINTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Multiplicand A number that is to be multiplied by another
|
|
|
|
|
@param[in] Multiplier A number by which the multiplicand is to be multiplied
|
|
|
|
|
@param[out] Result Pointer to the result of multiplication
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful multiplication
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeUintnMult (
|
|
|
|
|
IN UINTN Multiplicand,
|
|
|
|
|
IN UINTN Multiplier,
|
|
|
|
|
OUT UINTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
UINT64 IntermediateResult;
|
|
|
|
|
|
|
|
|
|
IntermediateResult = ((UINT64) Multiplicand) *((UINT64) Multiplier);
|
|
|
|
|
|
|
|
|
|
return SafeUint64ToUintn (IntermediateResult, Result);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
INTN Addition
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Augend A number to which addend will be added
|
|
|
|
|
@param[in] Addend A number to be added to another
|
|
|
|
|
@param[out] Result Pointer to the result of addition
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful addition
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeIntnAdd (
|
|
|
|
|
IN INTN Augend,
|
|
|
|
|
IN INTN Addend,
|
|
|
|
|
OUT INTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
return SafeInt64ToIntn (((INT64)Augend) + ((INT64)Addend), Result);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
INTN Subtraction
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Minuend A number from which another is to be subtracted.
|
|
|
|
|
@param[in] Subtrahend A number to be subtracted from another
|
|
|
|
|
@param[out] Result Pointer to the result of subtraction
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful subtraction
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Underflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeIntnSub (
|
|
|
|
|
IN INTN Minuend,
|
|
|
|
|
IN INTN Subtrahend,
|
|
|
|
|
OUT INTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
|
|
|
|
return SafeInt64ToIntn (((INT64)Minuend) - ((INT64)Subtrahend), Result);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/**
|
|
|
|
|
INTN multiplication
|
|
|
|
|
|
|
|
|
|
Performs the requested operation using the input parameters into a value
|
|
|
|
|
specified by Result type and stores the converted value into the caller
|
|
|
|
|
allocated output buffer specified by Result. The caller must pass in a
|
|
|
|
|
Result buffer that is at least as large as the Result type.
|
|
|
|
|
|
|
|
|
|
If Result is NULL, RETURN_INVALID_PARAMETER is returned.
|
|
|
|
|
|
|
|
|
|
If the requested operation results in an overflow or an underflow condition,
|
|
|
|
|
then Result is set to INTN_ERROR and RETURN_BUFFER_TOO_SMALL is returned.
|
|
|
|
|
|
|
|
|
|
@param[in] Multiplicand A number that is to be multiplied by another
|
|
|
|
|
@param[in] Multiplier A number by which the multiplicand is to be multiplied
|
|
|
|
|
@param[out] Result Pointer to the result of multiplication
|
|
|
|
|
|
|
|
|
|
@retval RETURN_SUCCESS Successful multiplication
|
|
|
|
|
@retval RETURN_BUFFER_TOO_SMALL Overflow
|
|
|
|
|
@retval RETURN_INVALID_PARAMETER Result is NULL
|
|
|
|
|
**/
|
|
|
|
|
RETURN_STATUS
|
|
|
|
|
EFIAPI
|
|
|
|
|
SafeIntnMult (
|
|
|
|
|
IN INTN Multiplicand,
|
|
|
|
|
IN INTN Multiplier,
|
|
|
|
|
OUT INTN *Result
|
|
|
|
|
)
|
|
|
|
|
{
|
2018-02-26 04:55:15 +01:00
|
|
|
return SafeInt64ToIntn (MultS64x64 (Multiplicand, Multiplier), Result);
|
MdePkg/BaseSafeIntLib: Add SafeIntLib class and instance
https://bugzilla.tianocore.org/show_bug.cgi?id=798
SafeIntLib provides helper functions to prevent integer overflow
during type conversion, addition, subtraction, and multiplication.
Conversion Functions
====================
* Converting from a signed type to an unsigned type of the same
size, or vice-versa.
* Converting to a smaller type that could possibly overflow.
* Converting from a signed type to a larger unsigned type.
Unsigned Addition, Subtraction, Multiplication
===============================================
* Unsigned integer math functions protect from overflow and
underflow (in case of subtraction).
Signed Addition, Subtraction, Multiplication
============================================
* Strongly consider using unsigned numbers.
* Signed numbers are often used where unsigned numbers should
be used. For example file sizes and array indices should always
be unsigned. Subtracting a larger positive signed number from a
smaller positive signed number with SafeInt32Sub() will succeed,
producing a negative number, that then must not be used as an
array index (but can occasionally be used as a pointer index.)
Similarly for adding a larger magnitude negative number to a
smaller magnitude positive number.
* SafeIntLib does not protect you from such errors. It tells you
if your integer operations overflowed, not if you are doing the
right thing with your non-overflowed integers.
* Likewise you can overflow a buffer with a non-overflowed
unsigned index.
Based on content from the following branch/commits:
https://github.com/Microsoft/MS_UEFI/tree/share/MsCapsuleSupport
https://github.com/Microsoft/MS_UEFI/commit/21ef3a321c907b40fa93797619c9f6c686dd92e0
https://github.com/Microsoft/MS_UEFI/commit/ca516b1a61315c2d823f453e12d2135098f53d61
https://github.com/Microsoft/MS_UEFI/commit/33bab4031a417d7d5a7d356c15a14c2e60302b2d
Cc: Sean Brogan <sean.brogan@microsoft.com>
Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Michael D Kinney <michael.d.kinney@intel.com>
Reviewed-by: Sean Brogan <sean.brogan@microsoft.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>
2017-04-25 01:37:20 +02:00
|
|
|
}
|
|
|
|
|
|
