Re: [PATCH (sh-2.6) 1/2] sh: add stack smashing protection support

[Carmelo AMOROSO <carmelo.amoroso@st.com>]

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On 12/9/2010 5:07 PM, Mike Frysinger wrote:
> On Thursday, December 09, 2010 10:56:26 Carmelo AMOROSO wrote:
>> I agree with you that the Kconfig and Makefile changes are not arch
>> specific, so these changes can be moved to a common code (even if I
>> don't know if other archs do support SSP).
>> In the current kernel, only x86 and ARM added this support, so I'm
>> wondering if, moving SSP to the common Makefile, it needs to depend on
>> x86, ARM, SH being configured ?
> 
> i'm not sure it does.  ssp is designed to be arch independent, so really you 
> only need a new enough gcc version.  which means i dont think it needs to 
> depend on any arch code and you can simply add to the Makefile a compiler 
> check.
> 
agreed, but if arch wants to implement the per-task canary feature, some
change into arch specific code is required.

>> Regarding the __stack_chk_guard symbol defined in process[_32].c, I
>> don't know if all archs need to define this global variable to implement
>> SSP. For sure x86 does not need it. It depends on how the gcc implements
>> this feature. This was mainly the reason for which we defined it
>> specifically in an arch specific code.
> 
> the common gcc code too outputs __stack_chk_guard references.  none of that is 
> in arch-specific places.

a simple test on x86 just prints reference to __stack_chk_fail only (not
reference to the global variable guard)

gcc is 4.3.0-8 (Fedora C9)

> -mike

carmelo

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