linux-kernel - [PATCH 2/2] soc: imx: gpc: Do not pass static memory as platform data

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Message-Id: <20180110161608.13015-2-andrew.smirnov@gmail.com>
Date:   Wed, 10 Jan 2018 08:16:08 -0800
From:   Andrey Smirnov <andrew.smirnov@...il.com>
To:     Shawn Guo <shawnguo@...nel.org>
Cc:     Andrey Smirnov <andrew.smirnov@...il.com>,
        Stefan Agner <stefan@...er.ch>,
        Lucas Stach <l.stach@...gutronix.de>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/2] soc: imx: gpc: Do not pass static memory as platform data

Platform device core assumes the ownership of dev.platform_data as
well as that it is dynamically allocated and it will try to kfree it
as a part of platform_device_release(). Change the code to pass
kzalloc'ed chunk of memory instead of a pointer to a static memory to
avoid causing a BUG() when calling platform_device_put().

The problem can be reproduced by artificially enabling the error path
of platform_device_add() call (around line 452).

Cc: Shawn Guo <shawnguo@...nel.org>
Cc: Stefan Agner <stefan@...er.ch>
Cc: Lucas Stach <l.stach@...gutronix.de>
Cc: linux-arm-kernel@...ts.infradead.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
---

This patch is a follow up to fix one of the bugs discussed in
lkml.kernel.org/r/3f836677c6e98aaf01bc1ac8c3410083@...er.ch

 drivers/soc/imx/gpc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/imx/gpc.c b/drivers/soc/imx/gpc.c
index 47e7aa963dbb..ec8b79abebac 100644
--- a/drivers/soc/imx/gpc.c
+++ b/drivers/soc/imx/gpc.c
@@ -18,6 +18,7 @@
 #include <linux/pm_domain.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/slab.h>
 
 #define GPC_CNTR		0x000
 
@@ -428,13 +429,19 @@ static int imx_gpc_probe(struct platform_device *pdev)
 			if (domain_index >= of_id_data->num_domains)
 				continue;
 
-			domain = &imx_gpc_domains[domain_index];
+			domain = kzalloc(sizeof(*domain), GFP_KERNEL);
+			if (!domain) {
+				of_node_put(np);
+				return -ENOMEM;
+			}
+			memcpy(domain, &imx_gpc_domains[domain_index], sizeof(*domain));
 			domain->regmap = regmap;
 			domain->ipg_rate_mhz = ipg_rate_mhz;
 
 			pd_pdev = platform_device_alloc("imx-pgc-power-domain",
 							domain_index);
 			if (!pd_pdev) {
+				kfree(domain);
 				of_node_put(np);
 				return -ENOMEM;
 			}
-- 
2.14.3