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Thu, 12 Mar 2020 10:56:47 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 02CAq7Sj143760; Thu, 12 Mar 2020 10:56:47 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2yqgvcnj54-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 12 Mar 2020 10:56:47 +0000 Received: from abhmp0020.oracle.com (abhmp0020.oracle.com [141.146.116.26]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 02CAujKB029016; Thu, 12 Mar 2020 10:56:45 GMT Received: from mwanda (/41.57.98.10) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 12 Mar 2020 03:56:44 -0700 Date: Thu, 12 Mar 2020 13:56:37 +0300 From: Dan Carpenter To: Peter Zijlstra , Ian Rogers Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: [PATCH] perf/core: Fix reversed NULL check in perf_event_groups_less() Message-ID: <20200312105637.GA8960@mwanda> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Mailer: git-send-email haha only kidding User-Agent: Mutt/1.10.1 (2018-07-13) X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9557 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 mlxscore=0 malwarescore=0 adultscore=0 phishscore=0 bulkscore=0 mlxlogscore=999 suspectscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003120059 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9557 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 lowpriorityscore=0 spamscore=0 priorityscore=1501 impostorscore=0 bulkscore=0 suspectscore=0 phishscore=0 mlxlogscore=999 mlxscore=0 malwarescore=0 clxscore=1011 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2001150001 definitions=main-2003120059 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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