backlight: pcf50633: pdata may be a null pointer, null pointer dereference cause crash

Started by Wenjia Zhao on Feb 1, 2021 · 3 messages from 3 authors · Last reply Feb 2, 2021

Subsystems (3)

Maintainers (5)

Show 1 more
STALE2108d

open the first message on its own page

Wenjia Zhao

Message details and related content
Open message details and related content
Signed-off-by: Wenjia Zhao <redacted>
---
 drivers/video/backlight/pcf50633-backlight.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c
index 540dd338..43267af 100644
--- a/drivers/video/backlight/pcf50633-backlight.c
+++ b/drivers/video/backlight/pcf50633-backlight.c
@@ -127,7 +127,8 @@ static int pcf50633_bl_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcf_bl);
 
-	pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
+  if (pdata)
+    pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
 
 	/*
 	 * Should be different from bl_props.brightness, so we do not exit
-- 
2.7.4

Lee Jones replied to Wenjia Zhao

Message details and related content
Open message details and related content
On Mon, 01 Feb 2021, Wenjia Zhao wrote:

Please provide a suitable commit messages.

Describe the problem.
Describe the issue was found.
Describe the solution.
quoted hunk
Signed-off-by: Wenjia Zhao <redacted>
---
 drivers/video/backlight/pcf50633-backlight.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c
index 540dd338..43267af 100644
--- a/drivers/video/backlight/pcf50633-backlight.c
+++ b/drivers/video/backlight/pcf50633-backlight.c
@@ -127,7 +127,8 @@ static int pcf50633_bl_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcf_bl);
 
-	pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
+  if (pdata)
+    pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
A tab should be 8 chars in Linux.

 	/*
 	 * Should be different from bl_props.brightness, so we do not exit
-- 
Lee Jones [李琼斯]
Senior Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog

Daniel Thompson replied to Wenjia Zhao

Message details and related content
Open message details and related content
On Mon, Feb 01, 2021 at 08:41:38AM -0600, Wenjia Zhao wrote:
Signed-off-by: Wenjia Zhao <redacted>
There should be a patch description here explaining why the patch
is needed and how it works.
quoted hunk
---
 drivers/video/backlight/pcf50633-backlight.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/video/backlight/pcf50633-backlight.c b/drivers/video/backlight/pcf50633-backlight.c
index 540dd338..43267af 100644
--- a/drivers/video/backlight/pcf50633-backlight.c
+++ b/drivers/video/backlight/pcf50633-backlight.c
@@ -127,7 +127,8 @@ static int pcf50633_bl_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, pcf_bl);
 
-	pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
+  if (pdata)
+    pcf50633_reg_write(pcf_bl->pcf, PCF50633_REG_LEDDIM, pdata->ramp_time);
Assuming you found this issue using a static analyzer then I think it
might be better to if an "if (!pdata) return -EINVAL" further up the
file instead.

In other words it is better to "document" (via the return code) that the
code does not support pdata == NULL than to add another untested code
path.


Daniel.
Keyboard shortcuts
hback out one level
jnext message in thread / next series-diff position
kprevious message in thread / previous series-diff position
ldrill in
Escclose help / fold thread tree
?toggle this help