linux-kernel - [RFT PATCH 3/3] rpmsg: fix kfree() of const memory on setting driver

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Message-Id: <20220222132707.266883-4-krzysztof.kozlowski@canonical.com>
Date:   Tue, 22 Feb 2022 14:27:07 +0100
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
To:     Abel Vesa <abel.vesa@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, linux-remoteproc@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, alsa-devel@...a-project.org
Cc:     Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        stable@...r.kernel.org
Subject: [RFT PATCH 3/3] rpmsg: fix kfree() of const memory on setting driver_override

The driver_override field from rpmsg_device should not be initialized
from const memory because the core later kfree() it, for example when
driver_override is set via sysfs.

Fixes: 950a7388f02b ("rpmsg: Turn name service into a stand alone driver")
Fixes: c0cdc19f84a4 ("rpmsg: Driver for user space endpoint interface")
Cc: <stable@...r.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>
---
 drivers/rpmsg/rpmsg_internal.h | 12 ++++++++++--
 drivers/rpmsg/rpmsg_ns.c       | 13 +++++++++++--
 2 files changed, 21 insertions(+), 4 deletions(-)

diff --git a/drivers/rpmsg/rpmsg_internal.h b/drivers/rpmsg/rpmsg_internal.h
index b1245d3ed7c6..c21e73ffbf05 100644
--- a/drivers/rpmsg/rpmsg_internal.h
+++ b/drivers/rpmsg/rpmsg_internal.h
@@ -92,10 +92,18 @@ int rpmsg_release_channel(struct rpmsg_device *rpdev,
  */
 static inline int rpmsg_chrdev_register_device(struct rpmsg_device *rpdev)
 {
+	int ret;
+
 	strcpy(rpdev->id.name, "rpmsg_chrdev");
-	rpdev->driver_override = "rpmsg_chrdev";
+	rpdev->driver_override = kstrdup("rpmsg_chrdev", GFP_KERNEL);
+	if (!rpdev->driver_override)
+		return -ENOMEM;
+
+	ret = rpmsg_register_device(rpdev);
+	if (ret)
+		kfree(rpdev->driver_override);
 
-	return rpmsg_register_device(rpdev);
+	return ret;
 }
 
 #endif
diff --git a/drivers/rpmsg/rpmsg_ns.c b/drivers/rpmsg/rpmsg_ns.c
index 762ff1ae279f..7d0605307d23 100644
--- a/drivers/rpmsg/rpmsg_ns.c
+++ b/drivers/rpmsg/rpmsg_ns.c
@@ -20,12 +20,21 @@
  */
 int rpmsg_ns_register_device(struct rpmsg_device *rpdev)
 {
+	int ret;
+
 	strcpy(rpdev->id.name, "rpmsg_ns");
-	rpdev->driver_override = "rpmsg_ns";
+	rpdev->driver_override = kstrdup("rpmsg_ns", GFP_KERNEL);
+	if (!rpdev->driver_override)
+		return -ENOMEM;
+
 	rpdev->src = RPMSG_NS_ADDR;
 	rpdev->dst = RPMSG_NS_ADDR;
 
-	return rpmsg_register_device(rpdev);
+	ret = rpmsg_register_device(rpdev);
+	if (ret)
+		kfree(rpdev->driver_override);
+
+	return ret;
 }
 EXPORT_SYMBOL(rpmsg_ns_register_device);
 
-- 
2.32.0