Re: [Xen-devel] [PATCH v2] fuzz/x86_emulate: fix bounds for input size

[Paul Semel <semelpaul@xxxxxxxxx>]

Hey George,

On 02/27/2018 11:39 AM, George Dunlap wrote:
> Thanks for the patch. Looking a bit more at the code over the weekend,
> I figured out what that BUILD_BUG_ON() is for -- in afl_harness.c, we
> statically allocate a buffer of size INPUT_SIZE to hold the fuzz data.
> The BUILD_BUG_ON() is to make sure that this buffer is always big enough
> to hold the minimum input size.  And increasing the size accepted by
> LLVMFuzzerTestOneInput() won't have any effect for anybody using
> afl-harness, as the size passed in will never be larger than INPUT_SIZE.
Thanks for replying me ! Actually, I understood what this BUILD_BUG_ON() was for 
and I totally agree with you 🙂
Anyway, I am pretty sure that this check is not needed anymore for the new 
changes I made, as the condition is never reachable anymore.
> Are you running afl-harness, or are you using fuzz-emul directly some
> other way (e.g., through Google's fuzzing service)?
I am actually not using it, but I discovered this tool some time before, and I 
am now trying to port the idea on an other emulator project.. 🙂
Anyway, I made much changes on my own version, and if it still does interest 
you, I can share those changes with you once I'm done with my thing !
>  -George
--
Paul

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