This is a note to let you know that I've just added the patch titled
auxdisplay: charlcd: checking for pointer reference before dereferencing
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
auxdisplay-charlcd-checking-for-pointer-reference-be.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b637f956500cf4fce047ab5fe998fe4c6d84c2be
Author: Luiz Sampaio <sampaio.ime@xxxxxxxxx>
Date: Tue Nov 9 19:07:32 2021 -0300
auxdisplay: charlcd: checking for pointer reference before dereferencing
[ Upstream commit 4daa9ff89ef27be43c15995412d6aee393a78200 ]
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 <sampaio.ime@xxxxxxxxx>
Signed-off-by: Miguel Ojeda <ojeda@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/auxdisplay/charlcd.c b/drivers/auxdisplay/charlcd.c
index 304accde365c8..6c010d4efa4ae 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;
