linux-kernel - Re: [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL 'struct perf_counts

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YVG8RM+ofI25Rk2r@kernel.org>
Date:   Mon, 27 Sep 2021 09:42:44 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Like Xu <like.xu.linux@...il.com>
Cc:     Ian Rogers <irogers@...gle.com>,
        Alexander Antonov <alexander.antonov@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Stephane Eranian <eranian@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] perf iostat: Fix Segmentation fault from NULL
 'struct perf_counts_values *'

Em Mon, Sep 27, 2021 at 04:11:15PM +0800, Like Xu escreveu:
> From: Like Xu <likexu@...cent.com>
> 
> If the perf-iostat user specifies two or more iio_root_ports and
> also specifies the cpu(s) by -C which is not *connected to all*
> the above iio ports, the iostat_print_metric() will run into trouble:
> 
> For example:
> 
>  $ perf iostat list
>  S0-uncore_iio_0<0000:16>
>  S1-uncore_iio_0<0000:97> # <--- CPU 1 is located in the socket S0
> 
>  $ perf iostat 0000:16,0000:97 -C 1 -- ls
>  port 	Inbound Read(MB)	Inbound Write(MB)	Outbound Read(MB)	Outbound
>  Write(MB) ../perf-iostat: line 12: 104418 Segmentation fault
>  (core dumped) perf stat --iostat$DELIMITER$*
> 
> The core-dump stack says, in the above corner case, the returned
> (struct perf_counts_values *) count will be NULL, and the caller
> iostat_print_metric() apparently doesn't not handle this case.
> 
>  433	struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
>  434
>  435	if (count->run && count->ena) {
>  (gdb) p count
>  $1 = (struct perf_counts_values *) 0x0
> 
> The deeper reason is that there are actually no statistics from the user
> specified pair "iostat 0000:X, -C (disconnected) Y ", but let's fix it with
> minimum cost by adding a NULL check in the user space.

Added:

Fixes: f9ed693e8bc0e7de ("perf stat: Enable iostat mode for x86 platforms")

Please do that next time,

- Arnaldo
 
> Signed-off-by: Like Xu <likexu@...cent.com>
> ---
>  tools/perf/arch/x86/util/iostat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/arch/x86/util/iostat.c b/tools/perf/arch/x86/util/iostat.c
> index eeafe97b8105..792cd75ade33 100644
> --- a/tools/perf/arch/x86/util/iostat.c
> +++ b/tools/perf/arch/x86/util/iostat.c
> @@ -432,7 +432,7 @@ void iostat_print_metric(struct perf_stat_config *config, struct evsel *evsel,
>  	u8 die = ((struct iio_root_port *)evsel->priv)->die;
>  	struct perf_counts_values *count = perf_counts(evsel->counts, die, 0);
>  
> -	if (count->run && count->ena) {
> +	if (count && count->run && count->ena) {
>  		if (evsel->prev_raw_counts && !out->force_header) {
>  			struct perf_counts_values *prev_count =
>  				perf_counts(evsel->prev_raw_counts, die, 0);
> -- 
> 2.32.0

-- 

- Arnaldo