On Fri, Nov 23, 2012 at 9:38 AM, Jakub Jelinek <ja...@redhat.com> wrote:
> On Fri, Nov 23, 2012 at 09:23:37AM -0800, H.J. Lu wrote:
>> This patch allocates extra 16 bytes for -fsanitize=address so that
>> asan won't report read beyond memory buffer. It is used by
>> bootstrap-asan. OK to install?
>
> As valgrind warns about that too, I'd say we should do that unconditionally,
> the additional 16-bytes just aren't a big deal.
This isn't sufficient for valgrind since valgrind will also report
reading uninitialized data, which requires additional memset
on extra 16 bytes.
> But, _cpp_convert_input isn't the only place which needs that, IMHO you want
This patch is sufficient to compile libcpp with -fsanitize=address.
> to also change the caller, read_file_guts, where it does
> buf = XNEWVEC (uchar, size + 1);
> and
> buf = XRESIZEVEC (uchar, buf, size + 1);
I don't think it is necessary since there is no real data in
those extra 16 bytes. They can have garbage and libcpp still
functions correctly. They are purely used to silence ASAN.
> I'll defer the review to Tom though.
>
>> 2012-11-21 H.J. Lu <hongjiu...@intel.com>
>>
>> PR bootstrap/55380
>> * charset.c (_cpp_convert_input): Allocate extra 16 bytes for
>> -fsanitize=address if __SANITIZE_ADDRESS__ is defined.
>>
>> diff --git a/libcpp/charset.c b/libcpp/charset.c
>> index cba19a6..dea8bb1 100644
>> --- a/libcpp/charset.c
>> +++ b/libcpp/charset.c
>> @@ -1729,9 +1729,16 @@ _cpp_convert_input (cpp_reader *pfile, const char
>> *input_charset,
>> iconv_close (input_cset.cd);
>>
>> /* Resize buffer if we allocated substantially too much, or if we
>> - haven't enough space for the \n-terminator. */
>> + haven't enough space for the \n-terminator. Allocate extra 16
>> + bytes for -fsanitize=address. */
>> if (to.len + 4096 < to.asize || to.len >= to.asize)
>> - to.text = XRESIZEVEC (uchar, to.text, to.len + 1);
>> + {
>> +#ifdef __SANITIZE_ADDRESS__
>> + to.text = XRESIZEVEC (uchar, to.text, to.len + 17);
>> +#else
>> + to.text = XRESIZEVEC (uchar, to.text, to.len + 1);
>> +#endif
>> + }
>>
>> /* If the file is using old-school Mac line endings (\r only),
>> terminate with another \r, not an \n, so that we do not mistake
>
> Jakub
--
H.J.
