linux-kernel - [PATCH] of: do not leak console options

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Date:   Tue, 26 Sep 2017 15:25:10 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Subject: [PATCH] of: do not leak console options

Do not strdup() console options. It seems that the only reason for
it to be strdup()-ed was a compilation warning: printk, UART and
console drivers, for some reason, expect char pointer instead of
const char pointer. So we can just pass `of_stdout_options', but
need to cast it to char pointer. A better fix would be to change
printk, console drivers and UART to accept const char `options';
but that will take time - there are lots of drivers to update.

The patch also fixes a possible memory leak: add_preferred_console()
can fail, but we don't kfree() options.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
---
 drivers/of/base.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index 260d33c0f26c..63897531cd75 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1781,8 +1781,12 @@ bool of_console_check(struct device_node *dn, char *name, int index)
 {
 	if (!dn || dn != of_stdout || console_set_on_cmdline)
 		return false;
-	return !add_preferred_console(name, index,
-				      kstrdup(of_stdout_options, GFP_KERNEL));
+
+	/*
+	 * XXX: cast `options' to char pointer to suppress complication
+	 * warnings: printk, UART and console drivers expect char pointer.
+	 */
+	return !add_preferred_console(name, index, (char *)of_stdout_options);
 }
 EXPORT_SYMBOL_GPL(of_console_check);

-- 
2.14.1