linux-kernel - [PATCH 4.19 083/148] media: media/dvb: Use kmemdup rather than duplicating its implementation

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Date: Sun, 24 Mar 2024 19:49:07 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Fuqian Huang <huangfq.daxian@...il.com>,
	Sean Young <sean@...s.org>,
	Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
	Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 083/148] media: media/dvb: Use kmemdup rather than duplicating its implementation

From: Fuqian Huang <huangfq.daxian@...il.com>

[ Upstream commit f6af820ef1be58c2e4b81aa479b9f109eb6344ce ]

kmemdup is introduced to duplicate a region of memory in a neat way.
Rather than kmalloc/kzalloc + memcpy, which the programmer needs to
write the size twice (sometimes lead to mistakes), kmemdup improves
readability, leads to smaller code and also reduce the chances of mistakes.
Suggestion to use kmemdup rather than using kmalloc/kzalloc + memcpy.

Signed-off-by: Fuqian Huang <huangfq.daxian@...il.com>
Signed-off-by: Sean Young <sean@...s.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@...nel.org>
Stable-dep-of: 8c64f4cdf4e6 ("media: edia: dvbdev: fix a use-after-free")
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/media/dvb-core/dvbdev.c             | 3 +--
 drivers/media/dvb-frontends/drx39xyj/drxj.c | 5 ++---
 2 files changed, 3 insertions(+), 5 deletions(-)

diff --git a/drivers/media/dvb-core/dvbdev.c b/drivers/media/dvb-core/dvbdev.c
index 1f80c4fa31c9b..5d68ad0ac5d26 100644
--- a/drivers/media/dvb-core/dvbdev.c
+++ b/drivers/media/dvb-core/dvbdev.c
@@ -485,7 +485,7 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
 		return -ENOMEM;
 	}
 
-	dvbdevfops = kzalloc(sizeof(struct file_operations), GFP_KERNEL);
+	dvbdevfops = kmemdup(template->fops, sizeof(*dvbdevfops), GFP_KERNEL);
 
 	if (!dvbdevfops){
 		kfree (dvbdev);
@@ -502,7 +502,6 @@ int dvb_register_device(struct dvb_adapter *adap, struct dvb_device **pdvbdev,
 	dvbdev->fops = dvbdevfops;
 	init_waitqueue_head (&dvbdev->wait_queue);
 
-	memcpy(dvbdevfops, template->fops, sizeof(struct file_operations));
 	dvbdevfops->owner = adap->module;
 
 	list_add_tail (&dvbdev->list_head, &adap->device_list);
diff --git a/drivers/media/dvb-frontends/drx39xyj/drxj.c b/drivers/media/dvb-frontends/drx39xyj/drxj.c
index 9670bc98b45a9..33cf6dccb547f 100644
--- a/drivers/media/dvb-frontends/drx39xyj/drxj.c
+++ b/drivers/media/dvb-frontends/drx39xyj/drxj.c
@@ -12287,7 +12287,8 @@ struct dvb_frontend *drx39xxj_attach(struct i2c_adapter *i2c)
 	if (state == NULL)
 		goto error;
 
-	demod = kmalloc(sizeof(struct drx_demod_instance), GFP_KERNEL);
+	demod = kmemdup(&drxj_default_demod_g,
+			sizeof(struct drx_demod_instance), GFP_KERNEL);
 	if (demod == NULL)
 		goto error;
 
@@ -12311,8 +12312,6 @@ struct dvb_frontend *drx39xxj_attach(struct i2c_adapter *i2c)
 	state->demod = demod;
 
 	/* setup the demod data */
-	memcpy(demod, &drxj_default_demod_g, sizeof(struct drx_demod_instance));
-
 	demod->my_i2c_dev_addr = demod_addr;
 	demod->my_common_attr = demod_comm_attr;
 	demod->my_i2c_dev_addr->user_data = state;
-- 
2.43.0