2021-11-10 00:24:40

by Luiz Sampaio

Subject: [PATCH v2 2/2] auxdisplay: charlcd: checking for pointer reference before dereferencing

Check if the pointer lcd->ops->init_display exists before dereferencing it.
If a driver called charlcd_init() without defining the ops, this would
return segmentation fault, as happened to me when implementing a charlcd
driver. Checking the pointer before dereferencing protects from
segmentation fault.

Signed-off-by: Luiz Sampaio <[email protected]>
---
drivers/auxdisplay/charlcd.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index cca3b600c0ba..6d309e4971b6 100644
--- a/drivers/auxdisplay/charlcd.c
+++ b/drivers/auxdisplay/charlcd.c
@@ -578,6 +578,9 @@ static int charlcd_init(struct charlcd *lcd)
* Since charlcd_init_display() needs to write data, we have to
* enable mark the LCD initialized just before.
*/
+ if (WARN_ON(!lcd->ops->init_display))
+ return -EINVAL;
+
ret = lcd->ops->init_display(lcd);
if (ret)
return ret;
--
2.33.1

2021-11-24 11:02:08

by Miguel Ojeda

Subject: Re: [PATCH v2 2/2] auxdisplay: charlcd: checking for pointer reference before dereferencing

On Tue, Nov 9, 2021 at 11:07 PM Luiz Sampaio <[email protected]> wrote:
>
> Check if the pointer lcd->ops->init_display exists before dereferencing it.
> If a driver called charlcd_init() without defining the ops, this would
> return segmentation fault, as happened to me when implementing a charlcd
> driver. Checking the pointer before dereferencing protects from
> segmentation fault.
>
> Signed-off-by: Luiz Sampaio <[email protected]>

Queued up, thanks!

Cheers,
Miguel