linux-kernel - Re: [PATCH 1/2] perf probe: Only call probe_file__get

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Message-ID: <20151105155830.GV13236@kernel.org>
Date:	Thu, 5 Nov 2015 12:58:30 -0300
From:	'Arnaldo Carvalho de Melo' <acme@...nel.org>
To:	平松雅巳 / HIRAMATU，MASAMI 
	<masami.hiramatsu.pt@...achi.com>
Cc:	Wang Nan <wangnan0@...wei.com>,
	"namhyung@...nel.org" <namhyung@...nel.org>,
	"lizefan@...wei.com" <lizefan@...wei.com>,
	"pi3orama@....com" <pi3orama@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"jolsa@...nel.org" <jolsa@...nel.org>
Subject: Re: [PATCH 1/2] perf probe: Only call probe_file__get_events() when
 fd is valid

Em Thu, Nov 05, 2015 at 03:07:23PM +0000, 平松雅巳 / HIRAMATU，MASAMI escreveu:
> From: Arnaldo Carvalho de Melo [mailto:acme@...nel.org]
> >Em Thu, Nov 05, 2015 at 01:19:24PM +0000, Wang Nan escreveu:
> >> In system with kprobe enabled but uprobe turned off, 'perf probe -d'
> >> causes segfault because it calls probe_file__get_events() with a
> >> negative fd (when deleting uprobe events).
> >>
> >> This patch validates fds before calling probe_file__get_events().
> >
> >Wouldn't this shorter patch be more robust by deferring the validation
> >to just before using the 'fd' value?
> >
> >The end result is that probe_file__get_events() will return -ENOENT in
> >both calls, so ret and ret2 will both be set to -ENOENT, as in your
> >patch.
> >
> >Masami?
> 
> Yes, I've suggested so :)

Kinda, you suggested to check at probe_file__get_events() , while I am
suggesting to check even deeper, just before the actual use of fd, in
probe_file__get_rawlist().

- Arnaldo

> https://lkml.org/lkml/2015/11/5/353
> 
> Thanks!
> 
> 
> 
> >
> >- Arnaldo
> >
> >diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> >index 89dbeb92c68e..f04a8318a1a7 100644
> >--- a/tools/perf/util/probe-file.c
> >+++ b/tools/perf/util/probe-file.c
> >@@ -138,6 +138,9 @@ struct strlist *probe_file__get_rawlist(int fd)
> > 	char *p;
> > 	struct strlist *sl;
> >
> >+	if (fd < 0)
> >+		return NULL;
> >+
> > 	sl = strlist__new(NULL, NULL);
> >
> > 	fp = fdopen(dup(fd), "r");
> >
> >
> >diff --git a/tools/perf/util/probe-file.c b/tools/perf/util/probe-file.c
> >index 89dbeb92c68e..e5dc8e62f0f1 100644
> >--- a/tools/perf/util/probe-file.c
> >+++ b/tools/perf/util/probe-file.c
> >@@ -169,6 +169,9 @@ static struct strlist *__probe_file__get_namelist(int fd, bool include_group)
> > 	struct probe_trace_event tev;
> > 	int ret = 0;
> >
> >+	if (fd < 0)
> >+		return NULL;
> >+
> > 	memset(&tev, 0, sizeof(tev));
> > 	rawlist = probe_file__get_rawlist(fd);
> > 	if (!rawlist)
> >
> >
> >> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> >> Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
> >> Cc: Jiri Olsa <jolsa@...nel.org>
> >> Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
> >> Cc: Namhyung Kim <namhyung@...nel.org>
> >> ---
> >>  tools/perf/builtin-probe.c | 12 ++++++++++--
> >>  1 file changed, 10 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/tools/perf/builtin-probe.c b/tools/perf/builtin-probe.c
> >> index 132afc9..861aa89 100644
> >> --- a/tools/perf/builtin-probe.c
> >> +++ b/tools/perf/builtin-probe.c
> >> @@ -384,7 +384,11 @@ static int perf_del_probe_events(struct strfilter *filter)
> >>  		goto out;
> >>  	}
> >>
> >> -	ret = probe_file__get_events(kfd, filter, klist);
> >> +	if (kfd < 0)
> >> +		ret = -ENOENT;
> >> +	else
> >> +		ret = probe_file__get_events(kfd, filter, klist);
> >> +
> >>  	if (ret == 0) {
> >>  		strlist__for_each(ent, klist)
> >>  			pr_info("Removed event: %s\n", ent->s);
> >> @@ -394,7 +398,11 @@ static int perf_del_probe_events(struct strfilter *filter)
> >>  			goto error;
> >>  	}
> >>
> >> -	ret2 = probe_file__get_events(ufd, filter, ulist);
> >> +	if (ufd < 0)
> >> +		ret2 = -ENOENT;
> >> +	else
> >> +		ret2 = probe_file__get_events(ufd, filter, ulist);
> >> +
> >>  	if (ret2 == 0) {
> >>  		strlist__for_each(ent, ulist)
> >>  			pr_info("Removed event: %s\n", ent->s);
> >> --
> >> 1.8.3.4
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