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Re: [PATCH] Allocate extra 16 bytes for -fsanitize=address
- From: Jakub Jelinek <jakub at redhat dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>, Tom Tromey <tromey at redhat dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 23 Nov 2012 18:38:49 +0100
- Subject: Re: [PATCH] Allocate extra 16 bytes for -fsanitize=address
- References: <20121123172337.GA26106@gmail.com>
- Reply-to: Jakub Jelinek <jakub at redhat dot com>
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.
But, _cpp_convert_input isn't the only place which needs that, IMHO you want
to also change the caller, read_file_guts, where it does
buf = XNEWVEC (uchar, size + 1);
and
buf = XRESIZEVEC (uchar, buf, size + 1);
I'll defer the review to Tom though.
> 2012-11-21 H.J. Lu <hongjiu.lu@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