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5000568969
StackCheckLib contains the required functionality for initializing the stack cookie value, checking the value, and triggering an interrupt when a mismatch occurs. The stack cookie is a random value placed on the stack between the stack variables and the return address so that continuously writing past the stack variables will cause the stack cookie to be overwritten. Before the function returns, the stack cookie value will be checked and if there is a mismatch then StackCheckLib handles the failure. Because UEFI doesn't use the C runtime libraries provided by MSVC, the stack check code is written in assembly within this library. GCC and Clang compilers have built-in support for stack cookie checking, so this library only handles failures. Signed-off-by: Oliver Smith-Denny <osde@linux.microsoft.com>
44 lines
1.4 KiB
NASM
44 lines
1.4 KiB
NASM
;------------------------------------------------------------------------------
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; IA32/CheckCookieMsvc.nasm
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;
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; Copyright (c) Microsoft Corporation.
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; SPDX-License-Identifier: BSD-2-Clause-Patent
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;------------------------------------------------------------------------------
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DEFAULT REL
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SECTION .text
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extern ASM_PFX(StackCheckFailure)
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extern ASM_PFX(__security_cookie)
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extern ASM_PFX(CpuDeadLoop)
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; Called when a buffer check fails. This functionality is dependent on MSVC
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; C runtime libraries and so is unsupported in UEFI.
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global ASM_PFX(__report_rangecheckfailure)
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ASM_PFX(__report_rangecheckfailure):
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jmp ASM_PFX(CpuDeadLoop)
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ret
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; The GS handler is for checking the stack cookie during SEH or
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; EH exceptions and is unsupported in UEFI.
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global ASM_PFX(__GSHandlerCheck)
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ASM_PFX(__GSHandlerCheck):
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jmp ASM_PFX(CpuDeadLoop)
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ret
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;------------------------------------------------------------------------------
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; Checks the stack cookie value against __security_cookie and calls the
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; stack cookie failure handler if there is a mismatch.
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;
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; VOID
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; EFIAPI
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; __security_check_cookie (
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; IN UINTN CheckValue
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; );
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;------------------------------------------------------------------------------
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global @__security_check_cookie@4
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@__security_check_cookie@4:
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cmp ecx, [ASM_PFX(__security_cookie)]
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jne ASM_PFX(StackCheckFailure)
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ret
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