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

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Date:   Wed, 18 Dec 2019 18:03:07 +0100
From:   Andrey Zhizhikin <andrey.z@...il.com>
To:     Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
Cc:     ast@...nel.org, daniel@...earbox.net, kafai@...com,
        songliubraving@...com, yhs@...com, andriin@...com,
        sergey.senozhatsky@...il.com, pmladek@...e.com,
        wangkefeng.wang@...wei.com, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org, bpf@...r.kernel.org,
        Andrey Zhizhikin <andrey.zhizhikin@...ca-geosystems.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Jiri Olsa <jolsa@...nel.org>
Subject: Re: [PATCH] tools lib api fs: fix gcc9 compilation error

On Wed, Dec 18, 2019 at 3:33 PM Arnaldo Carvalho de Melo
<arnaldo.melo@...il.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@...ca-geosystems.com>
> > Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> > Cc: Jiri Olsa <jolsa@...nel.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.