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From: Mathieu Poirier <mathieu.poirier@linaro.org>
To: gregkh@linuxfoundation.org
Cc: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/2] coresight: etm3x: Smatch: Fix potential NULL pointer dereference
Date: Fri, 21 Jun 2019 11:52:04 -0600	[thread overview]
Message-ID: <20190621175205.24551-2-mathieu.poirier@linaro.org> (raw)
In-Reply-To: <20190621175205.24551-1-mathieu.poirier@linaro.org>

From: Suzuki K Poulose <suzuki.poulose@arm.com>

Based on the following report from  Smatch tool, make sure we have a
valid drvdata before we dereference it to find the real dev.

The patch 21d26b905c05: "coresight: etm: Clean up device specific
data" from May 22, 2019, leads to the following Smatch complaint:

    ./drivers/hwtracing/coresight/coresight-etm3x.c:460 etm_get_trace_id()
    warn: variable dereferenced before check 'drvdata' (see line 458)

./drivers/hwtracing/coresight/coresight-etm3x.c
   457		int trace_id = -1;
   458		struct device *etm_dev = drvdata->csdev->dev.parent;
                                         ^^^^^^^^^
New dereference

   459
   460		if (!drvdata)
                    ^^^^^^^^
Checked too late.  Delete the check?

   461			goto out;
   462

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-etm3x.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm3x.c b/drivers/hwtracing/coresight/coresight-etm3x.c
index bed729140718..225c2982e4fe 100644
--- a/drivers/hwtracing/coresight/coresight-etm3x.c
+++ b/drivers/hwtracing/coresight/coresight-etm3x.c
@@ -455,11 +455,12 @@ int etm_get_trace_id(struct etm_drvdata *drvdata)
 {
 	unsigned long flags;
 	int trace_id = -1;
-	struct device *etm_dev = drvdata->csdev->dev.parent;
+	struct device *etm_dev;
 
 	if (!drvdata)
 		goto out;
 
+	etm_dev = drvdata->csdev->dev.parent;
 	if (!local_read(&drvdata->mode))
 		return drvdata->traceid;
 
-- 
2.17.1


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  reply	other threads:[~2019-06-21 17:52 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-21 17:52 [PATCH 0/2] coresight: next v5.2-rc5 (Part 2) Mathieu Poirier
2019-06-21 17:52 ` Mathieu Poirier [this message]
2019-06-21 17:52 ` [PATCH 2/2] coresight: tmc: Smatch: Fix potential NULL pointer dereference Mathieu Poirier
  -- strict thread matches above, loose matches on Subject: below --
2019-06-13 10:06 [PATCH 1/2] coresight: etm3x: " Suzuki K Poulose
2019-06-17 19:28 ` Mathieu Poirier

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