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Re: [Xen-devel] [PATCH v3 01/12] fuzz/x86_emulate: Clear errors after each iteration



>>> On 10.10.17 at 19:22, <ian.jackson@xxxxxxxxxxxxx> wrote:
> George Dunlap writes ("[PATCH v3 01/12] fuzz/x86_emulate: Clear errors after 
> each iteration"):
>> Once feof() returns true for a stream, it will continue to return true
>> for that stream until clearerr() is called (or the stream is closed
>> and re-opened).
>> 
>> In llvm-clang-fast-mode, the same file descriptor is used for each
>> iteration of the loop, meaning that the "Input too large" check was
>> broken -- feof() would return true even if the fread() hadn't hit the
>> end of the file.  The result is that AFL generates testcases of
>> arbitrary size.
>> 
>> Fix this by fseek'ing to the beginning of the file on every iteration;
>> this resets the EOF marker and other state.
> 
> Acked-by: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
> 
>> This is a candidate for backport to 4.9.
> 
> Please let me know when it is committed and I will add it to my
> backport list.

I have the original one on mine already, so I can easily add this
one then as well; perhaps I would want to even fold the two into
just a single (good) commit).

Jan


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