LGTM, thanks :)
On Wed, Jan 19, 2022 at 12:59 AM Maciej W. Rozycki <ma...@embecosm.com> wrote:
>
> Avoid undefined arithmetic involving a pointer to a heap allocation that
> has been freed and move a problematic calculation ahead of the following
> call to `free' in `riscv_subset_list::parse_multiletter_ext', removing a
> compilation error:
>
> .../gcc/common/config/riscv/riscv-common.cc: In member function 'const char*
> riscv_subset_list::parse_multiletter_ext(const char*, const char*, const
> char*)':
> .../gcc/common/config/riscv/riscv-common.cc:905:27: error: pointer 'subset'
> used after 'void free(void*)' [-Werror=use-after-free]
> 905 | p += end_of_version - subset;
> | ~~~~~~~~~~~~~~~^~~~~~~~
> .../gcc/common/config/riscv/riscv-common.cc:904:12: note: call to 'void
> free(void*)' here
> 904 | free (subset);
> | ~~~~~^~~~~~~~
> cc1plus: all warnings being treated as errors
> make[2]: *** [Makefile:2428: riscv-common.o] Error 1
>
> and a build regression from commit 671a283636de ("Add -Wuse-after-free
> [PR80532].").
>
> gcc/
> * common/config/riscv/riscv-common.cc
> (riscv_subset_list::parse_multiletter_ext): Move pointer
> arithmetic ahead of `free'.
> ---
> gcc/common/config/riscv/riscv-common.cc | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> gcc-riscv-parse-multiletter-ext-free.diff
> Index: gcc/gcc/common/config/riscv/riscv-common.cc
> ===================================================================
> --- gcc.orig/gcc/common/config/riscv/riscv-common.cc
> +++ gcc/gcc/common/config/riscv/riscv-common.cc
> @@ -901,8 +901,8 @@ riscv_subset_list::parse_multiletter_ext
> }
>
> add (subset, major_version, minor_version, explicit_version_p, false);
> - free (subset);
> p += end_of_version - subset;
> + free (subset);
>
> if (*p != '\0' && *p != '_')
> {
