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Re: [PATCHv4] Enable -fsanitize-recover for KASan


On 10/23/2014 02:38 PM, Jakub Jelinek wrote:
> On Thu, Oct 23, 2014 at 02:33:42PM +0400, Yury Gribov wrote:
>> Actually this is a historical artifact.  If inlining proves to be
>> significantly faster, they may want to switch.
> 
> Ok.
> 
>>> So, at that point you can include your ugly hacks in __asan_load* logic in
>>> the kernel, the difference between __asan_load4 and __asan_load4_noabort
>>> will be just that the latter will always return, while the former will not
>>> if some error has been reported.
>>> All the __asan_load* and __asan_store* entrypoints, regardless of
>>> -f{,no-}sanitize-recover=kernel-address are by definition not noreturn, they
>>> in the common case (if the code is not buggy) return.
>>
>> Perhaps we should just keep __asan_load* as is and leave the decision
>> whether to abort or continue for the runtime?  This would make semantics of
>> -fsanitize-recover cumbersome though (because it wouldn't work if user
>> selects outline instrumentation).
> 
> Well, the "don't ever report anything while some per-CPU flag is set" thing
> can be considered as part of the "is this memory access ok" test, it is
> pretending everything is accessible.
> 
> But, otherwise, if it is supposed to be developer's decision at compile
> time, __asan_load*_noabort should better always continue, even if it
> reported issues, and __asan_load* should better not return after reporting
> errors.
> 

True, but why we need new functions for that.
__asan_load could also abort or not depending on what user/developer wants.
Why we have to rebuild the entire kernel if someone wants to switch from abort to noabort?

I'm not against __asan_load_noabort, I'm just saying that this is no point to have separate
__asan_load/__asan_load_noabort functions in kernel.


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