From: Leo Yan <leo.yan@linaro.org>
To: Adrian Hunter <adrian.hunter@intel.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Mathieu Poirier <mathieu.poirier@linaro.org>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Andi Kleen <ak@linux.intel.com>,
"David S. Miller" <davem@davemloft.net>,
Davidlohr Bueso <dave@stgolabs.net>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Jin Yao <yao.jin@linux.intel.com>,
Song Liu <songliubraving@fb.com>,
Alexios Zavras <alexios.zavras@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Changbin Du <changbin.du@intel.com>,
Eric Saint-Etienne <eric.saint.etienne@oracle.com>,
Konstantin Khlebnikov <khlebnikov@yandex-team.ru>,
Thomas Richter <tmricht@linux.ibm.com>,
Alexey Budankov <alexey.budankov@linux.intel.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v1 10/11] perf intel-pt: Smatch: Fix potential NULL pointer dereference
Date: Wed, 3 Jul 2019 09:35:54 +0800 [thread overview]
Message-ID: <20190703013553.GB6852@leoy-ThinkPad-X240s> (raw)
In-Reply-To: <cfef1777-141e-4223-e0c1-1a3f3aee1d3c@intel.com>
Hi Adrian,
On Tue, Jul 02, 2019 at 02:07:40PM +0300, Adrian Hunter wrote:
> On 2/07/19 1:34 PM, Leo Yan wrote:
> > Based on the following report from Smatch, fix the potential
> > NULL pointer dereference check.
>
> It never is NULL. Remove the NULL test if you want:
>
> - if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
> + if (session->itrace_synth_opts->set) {
>
> But blindly making changes like below is questionable.
Thanks for suggestions.
I checked report and script commands, as you said, both command will
always set session->itrace_synth_opts. For these two commands, we can
safely remove the NULL test.
Because perf tool contains many sub commands, so I don't have much
confidence it's very safe to remove the NULL test for all cases; e.g.
there have cases which will process aux trace buffer but without
itrace options; for this case, session->itrace_synth_opts might be NULL.
For either way (remove NULL test or keep NULL test), I don't want to
introduce regression and extra efforts by my patch. So want to double
confirm with you for this :)
Thanks,
Leo Yan
> > tools/perf/util/intel-pt.c:3200
> > intel_pt_process_auxtrace_info() error: we previously assumed
> > 'session->itrace_synth_opts' could be null (see line 3196)
> >
> > tools/perf/util/intel-pt.c:3206
> > intel_pt_process_auxtrace_info() warn: variable dereferenced before
> > check 'session->itrace_synth_opts' (see line 3200)
> >
> > tools/perf/util/intel-pt.c
> > 3196 if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
> > 3197 pt->synth_opts = *session->itrace_synth_opts;
> > 3198 } else {
> > 3199 itrace_synth_opts__set_default(&pt->synth_opts,
> > 3200 session->itrace_synth_opts->default_no_sample);
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 3201 if (!session->itrace_synth_opts->default_no_sample &&
> > 3202 !session->itrace_synth_opts->inject) {
> > 3203 pt->synth_opts.branches = false;
> > 3204 pt->synth_opts.callchain = true;
> > 3205 }
> > 3206 if (session->itrace_synth_opts)
> > ^^^^^^^^^^^^^^^^^^^^^^^^^^
> > 3207 pt->synth_opts.thread_stack =
> > 3208 session->itrace_synth_opts->thread_stack;
> > 3209 }
> >
> > To dismiss the potential NULL pointer dereference, this patch validates
> > the pointer 'session->itrace_synth_opts' before access its elements.
> >
> > Signed-off-by: Leo Yan <leo.yan@linaro.org>
> > ---
> > tools/perf/util/intel-pt.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/tools/perf/util/intel-pt.c b/tools/perf/util/intel-pt.c
> > index 550db6e77968..88b567bdf1f9 100644
> > --- a/tools/perf/util/intel-pt.c
> > +++ b/tools/perf/util/intel-pt.c
> > @@ -3195,7 +3195,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
> >
> > if (session->itrace_synth_opts && session->itrace_synth_opts->set) {
> > pt->synth_opts = *session->itrace_synth_opts;
> > - } else {
> > + } else if (session->itrace_synth_opts) {
> > itrace_synth_opts__set_default(&pt->synth_opts,
> > session->itrace_synth_opts->default_no_sample);
> > if (!session->itrace_synth_opts->default_no_sample &&
> > @@ -3203,8 +3203,7 @@ int intel_pt_process_auxtrace_info(union perf_event *event,
> > pt->synth_opts.branches = false;
> > pt->synth_opts.callchain = true;
> > }
> > - if (session->itrace_synth_opts)
> > - pt->synth_opts.thread_stack =
> > + pt->synth_opts.thread_stack =
> > session->itrace_synth_opts->thread_stack;
> > }
> >
> >
>
next prev parent reply other threads:[~2019-07-03 1:36 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-02 10:34 [PATCH v1 00/11] perf: Fix errors detected by Smatch Leo Yan
2019-07-02 10:34 ` [PATCH v1 01/11] perf report: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-02 10:34 ` [PATCH v1 02/11] perf stat: Smatch: Fix use-after-freed pointer Leo Yan
2019-07-03 18:18 ` Arnaldo Carvalho de Melo
2019-07-13 10:53 ` [tip:perf/urgent] perf stat: Fix use-after-freed pointer detected by the smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 03/11] perf top: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-03 18:30 ` Arnaldo Carvalho de Melo
2019-07-13 10:53 ` [tip:perf/urgent] perf top: Fix potential NULL pointer dereference detected by the smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 04/11] perf annotate: Smatch: Fix dereferencing freed memory Leo Yan
2019-07-03 18:43 ` Arnaldo Carvalho de Melo
2019-07-13 10:54 ` [tip:perf/urgent] perf annotate: Fix dereferencing freed memory found by the smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 05/11] perf trace: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-03 18:46 ` Arnaldo Carvalho de Melo
2019-07-13 10:55 ` [tip:perf/urgent] perf trace: Fix potential NULL pointer dereference found by the smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 06/11] perf hists: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-02 11:07 ` Jiri Olsa
2019-07-02 10:34 ` [PATCH v1 07/11] perf map: " Leo Yan
2019-07-13 10:55 ` [tip:perf/urgent] perf map: Fix potential NULL pointer dereference found by smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 08/11] perf session: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-03 19:01 ` Arnaldo Carvalho de Melo
2019-07-13 10:57 ` [tip:perf/urgent] perf session: Fix potential NULL pointer dereference found by the smatch tool tip-bot for Leo Yan
2019-07-02 10:34 ` [PATCH v1 09/11] perf intel-bts: Smatch: Fix potential NULL pointer dereference Leo Yan
2019-07-02 10:34 ` [PATCH v1 10/11] perf intel-pt: " Leo Yan
2019-07-02 11:07 ` Adrian Hunter
2019-07-03 1:35 ` Leo Yan [this message]
2019-07-03 5:19 ` Adrian Hunter
2019-07-03 8:16 ` Leo Yan
2019-07-03 10:00 ` Daniel Thompson
2019-07-03 10:28 ` Leo Yan
2019-07-02 10:34 ` [PATCH v1 11/11] perf cs-etm: " Leo Yan
2019-07-02 17:03 ` Mathieu Poirier
2019-07-03 8:22 ` Leo Yan
2019-07-02 11:07 ` [PATCH v1 00/11] perf: Fix errors detected by Smatch Jiri Olsa
2019-07-03 1:48 ` Leo Yan
2019-07-03 18:18 ` Arnaldo Carvalho de Melo
2019-07-04 7:29 ` Leo Yan
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