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

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Date:	Thu, 5 Nov 2015 11:57:47 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	namhyung@...nel.org, lizefan@...wei.com, pi3orama@....com,
	linux-kernel@...r.kernel.org, jolsa@...nel.org,
	masami.hiramatsu.pt@...achi.com
Subject: Re: [PATCH 1/2] perf probe: Only call probe_file__get_events() when
 fd is valid

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?

- 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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