[PATCH 1/2] coresight: etm3x: Smatch: Fix potential NULL pointer dereference

[PATCH 1/2] coresight: etm3x: Smatch: Fix potential NULL pointer dereference

[Suzuki K Poulose]

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>
---
 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 bed7291..225c298 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;
 
-- 
2.7.4


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

[Suzuki K Poulose]

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>
---
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index 5d2bf6d..1700670 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);
 }
 
-- 
2.7.4


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Re: [PATCH 1/2] coresight: etm3x: Smatch: Fix potential NULL pointer dereference

[Mathieu Poirier]

On Thu, 13 Jun 2019 at 04:06, Suzuki K Poulose <suzuki.poulose@arm.com> wrote:
>
> 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>
> ---
>  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 bed7291..225c298 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;
>

I have applied both patches in this set.

Thanks,
Mathieu

> --
> 2.7.4
>

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[PATCH 0/2] coresight: next v5.2-rc5 (Part 2)

[Mathieu Poirier]

Good morning,

As requested these are two patches that were part of the original tally[1]
that should go on your char-misc-next for the 5.3 cycle.

Applies cleanly on char-misc-next (1a044213fc64).

Thanks,
Mathieu

[1]. https://www.spinics.net/lists/arm-kernel/msg736135.html 

Suzuki K Poulose (2):
  coresight: etm3x: Smatch: Fix potential NULL pointer dereference
  coresight: tmc: Smatch: Fix potential NULL pointer dereference

 drivers/hwtracing/coresight/coresight-etm3x.c   | 3 ++-
 drivers/hwtracing/coresight/coresight-tmc-etr.c | 6 ++++--
 2 files changed, 6 insertions(+), 3 deletions(-)

-- 
2.17.1


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

[Mathieu Poirier]

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 --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);
 }
 
-- 
2.17.1


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