diff mbox series

[2/2] coresight: tmc: Smatch: Fix potential NULL pointer dereference

Message ID 20190621175205.24551-3-mathieu.poirier@linaro.org (mailing list archive)
State Mainlined
Commit 17c20f329a139e90e4b049b811ca6d1a2ae967e0
Headers show
Series coresight: next v5.2-rc5 (Part 2) | expand

Commit Message

Mathieu Poirier June 21, 2019, 5:52 p.m. UTC 
From: Suzuki K Poulose <suzuki.poulose@arm.com>

Based on the following report from Smatch, fix the potential
NULL pointer dereference check.

The patch 743256e214e8: "coresight: tmc: Clean up device specific
data" from May 22, 2019, leads to the following Smatch complaint:

    drivers/hwtracing/coresight/coresight-tmc-etr.c:625 tmc_etr_free_flat_buf()
    warn: variable dereferenced before check 'flat_buf' (see line 623)

drivers/hwtracing/coresight/coresight-tmc-etr.c
   622		struct etr_flat_buf *flat_buf = etr_buf->private;
   623		struct device *real_dev = flat_buf->dev->parent;
                                          ^^^^^^^^^^
The patch introduces a new NULL check

   624
   625		if (flat_buf && flat_buf->daddr)
                    ^^^^^^^^
but the existing code assumed it can be NULL.

   626			dma_free_coherent(real_dev, flat_buf->size,
   627					  flat_buf->vaddr, flat_buf->daddr);

Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)
diff mbox series

Patch

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index ce0114a5435c..a9c797c2f926 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -620,11 +620,13 @@  static int tmc_etr_alloc_flat_buf(struct tmc_drvdata *drvdata,
 static void tmc_etr_free_flat_buf(struct etr_buf *etr_buf)
 {
 	struct etr_flat_buf *flat_buf = etr_buf->private;
-	struct device *real_dev = flat_buf->dev->parent;
 
-	if (flat_buf && flat_buf->daddr)
+	if (flat_buf && flat_buf->daddr) {
+		struct device *real_dev = flat_buf->dev->parent;
+
 		dma_free_coherent(real_dev, flat_buf->size,
 				  flat_buf->vaddr, flat_buf->daddr);
+	}
 	kfree(flat_buf);
 }