Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Mon, 23 Mar 2020 15:37:36 +0100
From:   Jiri Olsa <jolsa@redhat.com>
To:     "Jin, Yao" <yao.jin@linux.intel.com>
Cc:     acme@kernel.org, jolsa@kernel.org, peterz@infradead.org,
        mingo@redhat.com, alexander.shishkin@linux.intel.com,
        Linux-kernel@vger.kernel.org, ak@linux.intel.com,
        kan.liang@intel.com, yao.jin@intel.com
Subject: Re: [PATCH v2 00/14] perf: Stream comparison
Message-ID: <20200323143736.GI1534489@krava>
References: <20200313071118.11983-1-yao.jin@linux.intel.com>
 <20200323110514.GG1534489@krava>
 <ed2686f2-a370-4113-5148-e75c194b25bd@linux.intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Disposition: inline
In-Reply-To: <ed2686f2-a370-4113-5148-e75c194b25bd@linux.intel.com>
Content-Transfer-Encoding: quoted-printable
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Mon, Mar 23, 2020 at 09:59:13PM +0800, Jin, Yao wrote:
> Hi Jiri,
>=20
> On 3/23/2020 7:05 PM, Jiri Olsa wrote:
> > On Fri, Mar 13, 2020 at 03:11:04PM +0800, Jin Yao wrote:
> > > Sometimes, a small change in a hot function reducing the cycles of
> > > this function, but the overall workload doesn't get faster. It is
> > > interesting where the cycles are moved to.
> >=20
> > I'm getting compilation fail:
> >=20
> > 	  BUILD:   Doing 'make -j1' parallel build
> > 	  CC       util/srclist.o
> > 	util/srclist.c: In function =E2=80=98srclist__node_new=E2=80=99:
> > 	util/srclist.c:388:35: error: =E2=80=98%s=E2=80=99 directive output =
may be truncated writing up to 4095 bytes into a region of size 4091 [-We=
rror=3Dformat-truncation=3D]
> > 	  388 |  snprintf(cmd, sizeof(cmd), "diff %s %s",
> > 	      |                                   ^~
> > 	......
> > 	  456 |  ret =3D init_src_info(b_path, a_path, rel_path, &node->info=
);
> > 	      |                      ~~~~~~
> > 	In file included from /usr/include/stdio.h:867,
> > 			 from util/srclist.c:8:
> > 	/usr/include/bits/stdio2.h:67:10: note: =E2=80=98__builtin___snprint=
f_chk=E2=80=99 output between 7 and 8197 bytes into a destination of size=
 4096
> > 	   67 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_L=
EVEL - 1,
> > 	      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=
~~~~~~~~~
> > 	   68 |        __bos (__s), __fmt, __va_arg_pack ());
> > 	      |        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> > 	cc1: all warnings being treated as errors
> > 	mv: cannot stat 'util/.srclist.o.tmp': No such file or directory
> > 	make[4]: *** [/home/jolsa/kernel/linux-perf/tools/build/Makefile.bui=
ld:97: util/srclist.o] Error 1
> > 	make[3]: *** [/home/jolsa/kernel/linux-perf/tools/build/Makefile.bui=
ld:139: util] Error 2
> > 	make[2]: *** [Makefile.perf:617: perf-in.o] Error 2
> > 	make[1]: *** [Makefile.perf:225: sub-make] Error 2
> > 	make: *** [Makefile:70: all] Error 2
> >=20
> >=20
> > [jolsa@krava ~]$ gcc --version
> > gcc (GCC) 9.3.1 20200317 (Red Hat 9.3.1-1)
> >=20
> > jirka
> >=20
>=20
> Can you help to add following patch on top of the patch-set? Looks we n=
eed
> to check the return value of snprintf for truncation checking.

yep, that helped.. I'll apply it on top for now
and try to do the review soon ;-)

thanks,
jirka

>=20
> jinyao@kbl:~/kbl-ws/perf-dev/lck-7589/acme/tools/perf$ git diff
> diff --git a/tools/perf/util/srclist.c b/tools/perf/util/srclist.c
> index 8060e4855d11..51ca69eaa9fd 100644
> --- a/tools/perf/util/srclist.c
> +++ b/tools/perf/util/srclist.c
> @@ -385,8 +385,12 @@ static int src_info__create_line_mapping(struct
> src_info *info, char *b_path,
>                 goto out;
>         }
>=20
> -       snprintf(cmd, sizeof(cmd), "diff %s %s",
> -                b_path, a_path);
> +       ret =3D snprintf(cmd, PATH_MAX, "diff %s %s",
> +                      b_path, a_path);
> +       if (ret =3D=3D PATH_MAX) {
> +               ret =3D -1;
> +               goto out;
> +       }
>=20
>         pr_debug("Execute '%s'\n", cmd);
>=20
> Thanks
> Jin Yao
>=20