Re: [PATCH] tools lib api fs: fix gcc9 compilation error

Andrey Zhizhikin
2019-12-18T17:03:21Z

On Wed, Dec 18, 2019 at 3:33 PM Arnaldo Carvalho de Melo
<arnaldo.melo@gmail.com> wrote:
>
> Em Wed, Dec 11, 2019 at 08:01:09AM +0000, Andrey Zhizhikin escreveu:
> > GCC9 introduced string hardening mechanisms, which exhibits the error
> > during fs api compilation:
> >
> > error: '__builtin_strncpy' specified bound 4096 equals destination size
> > [-Werror=stringop-truncation]
> >
> > This comes when the length of copy passed to strncpy is is equal to
> > destination size, which could potentially lead to buffer overflow.
> >
> > There is a need to mitigate this potential issue by limiting the size of
> > destination by 1 and explicitly terminate the destination with NULL.
>
> Thanks, applied and collected the reviewed-by and acked-by provided,

Thanks a lot for review and collecting this patch!

>
> - Arnaldo
>
> > Signed-off-by: Andrey Zhizhikin <andrey.zhizhikin@leica-geosystems.com>
> > Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
> > Cc: Jiri Olsa <jolsa@kernel.org>
> > ---
> > tools/lib/api/fs/fs.c | 4 +++-
> > 1 file changed, 3 insertions(+), 1 deletion(-)
> >
> > diff --git a/tools/lib/api/fs/fs.c b/tools/lib/api/fs/fs.c
> > index 11b3885e833e..027b18f7ed8c 100644
> > --- a/tools/lib/api/fs/fs.c
> > +++ b/tools/lib/api/fs/fs.c
> > @@ -210,6 +210,7 @@ static bool fs__env_override(struct fs *fs)
> > size_t name_len = strlen(fs->name);
> > /* name + "_PATH" + '\0' */
> > char upper_name[name_len + 5 + 1];
> > +
> > memcpy(upper_name, fs->name, name_len);
> > mem_toupper(upper_name, name_len);
> > strcpy(&upper_name[name_len], "_PATH");
> > @@ -219,7 +220,8 @@ static bool fs__env_override(struct fs *fs)
> > return false;
> >
> > fs->found = true;
> > - strncpy(fs->path, override_path, sizeof(fs->path));
> > + strncpy(fs->path, override_path, sizeof(fs->path) - 1);
> > + fs->path[sizeof(fs->path) - 1] = '\0';
> > return true;
> > }
> >
> > --
> > 2.17.1
>
> --
>
> - Arnaldo

--
Regards,
Andrey.