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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>, Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [PATCH] perf/core: Fix reversed NULL check in perf_event_groups_less()
Date: Thu, 12 Mar 2020 13:56:37 +0300	[thread overview]
Message-ID: <20200312105637.GA8960@mwanda> (raw)

This NULL check is reversed so it leads to a Smatch warning and
presumably a NULL dereference.

    kernel/events/core.c:1598 perf_event_groups_less()
    error: we previously assumed 'right->cgrp->css.cgroup' could be null
	(see line 1590)

Fixes: 95ed6c707f26 ("perf/cgroup: Order events in RB tree by cgroup id")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6a47c3e54fe9..607c04ec7cfa 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1587,7 +1587,7 @@ perf_event_groups_less(struct perf_event *left, struct perf_event *right)
 			 */
 			return true;
 		}
-		if (!right->cgrp || right->cgrp->css.cgroup) {
+		if (!right->cgrp || !right->cgrp->css.cgroup) {
 			/*
 			 * Right has no cgroup but left does, no cgroups come
 			 * first.
-- 
2.20.1


WARNING: multiple messages have this Message-ID (diff)
From: Dan Carpenter <dan.carpenter@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>, Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
	linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org
Subject: [PATCH] perf/core: Fix reversed NULL check in perf_event_groups_less()
Date: Thu, 12 Mar 2020 10:56:37 +0000	[thread overview]
Message-ID: <20200312105637.GA8960@mwanda> (raw)

This NULL check is reversed so it leads to a Smatch warning and
presumably a NULL dereference.

    kernel/events/core.c:1598 perf_event_groups_less()
    error: we previously assumed 'right->cgrp->css.cgroup' could be null
	(see line 1590)

Fixes: 95ed6c707f26 ("perf/cgroup: Order events in RB tree by cgroup id")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 kernel/events/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 6a47c3e54fe9..607c04ec7cfa 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -1587,7 +1587,7 @@ perf_event_groups_less(struct perf_event *left, struct perf_event *right)
 			 */
 			return true;
 		}
-		if (!right->cgrp || right->cgrp->css.cgroup) {
+		if (!right->cgrp || !right->cgrp->css.cgroup) {
 			/*
 			 * Right has no cgroup but left does, no cgroups come
 			 * first.
-- 
2.20.1

             reply	other threads:[~2020-03-12 10:57 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-12 10:56 Dan Carpenter [this message]
2020-03-12 10:56 ` [PATCH] perf/core: Fix reversed NULL check in perf_event_groups_less() Dan Carpenter
2020-03-13 12:27 ` Peter Zijlstra
2020-03-13 12:27   ` Peter Zijlstra
2020-03-21  2:24   ` Ian Rogers
2020-03-21  2:24     ` Ian Rogers
2020-03-20 12:58 ` [tip: perf/core] " tip-bot2 for Dan Carpenter

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