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From: Luiz Sampaio <sampaio.ime@gmail.com>
To: ojeda@kernel.org
Cc: linux-kernel@vger.kernel.org, Luiz Sampaio <sampaio.ime@gmail.com>
Subject: [PATCH v2 2/2] auxdisplay: charlcd: checking for pointer reference before dereferencing
Date: Tue,  9 Nov 2021 19:07:32 -0300	[thread overview]
Message-ID: <20211109220732.7973-3-sampaio.ime@gmail.com> (raw)
In-Reply-To: <20211109220732.7973-1-sampaio.ime@gmail.com>

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@gmail.com>
---
 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


  parent reply	other threads:[~2021-11-09 22:07 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-07 15:03 [PATCH 0/2] Fixing bug that would segmentation fault Luiz Sampaio
2021-11-07 15:03 ` [PATCH 1/2] auxdisplay: charlcd: fixing coding style issue Luiz Sampaio
2021-11-08 12:01   ` Miguel Ojeda
2021-11-07 15:03 ` [PATCH 2/2] auxdisplay: charlcd: checking for pointer reference before dereferencing Luiz Sampaio
2021-11-08 11:58   ` Miguel Ojeda
2021-11-09 22:07     ` [PATCH v2 0/2] Fixing bug that would segmentation fault Luiz Sampaio
2021-11-09 22:07       ` [PATCH v2 1/2] auxdisplay: charlcd: fixing coding style issue Luiz Sampaio
2021-11-24 11:02         ` Miguel Ojeda
2021-11-09 22:07       ` Luiz Sampaio [this message]
2021-11-24 11:01         ` [PATCH v2 2/2] auxdisplay: charlcd: checking for pointer reference before dereferencing Miguel Ojeda

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