linux-kernel - [PATCH V3] clk: vc5: Add memory check to prevent oops

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Date:   Thu, 16 Jul 2020 07:26:20 -0500
From:   Adam Ford <aford173@...il.com>
To:     linux-clk@...r.kernel.org
Cc:     dan.carpenter@...cle.com, luca@...aceresoli.net,
        aford@...conembedded.com, Adam Ford <aford173@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, linux-kernel@...r.kernel.org
Subject: [PATCH V3] clk: vc5: Add memory check to prevent oops

When getting the names of the child nodes, kasprintf is used to
allocate memory which is used to create the string for the node
name.  Unfortunately, there is no memory check to determine
if this allocation fails, it may cause an error when trying
to get child node name.

This patch will check if the memory allocation fails, and returns
and -ENOMEM error instead of blindly moving on.

Fixes: 260249f929e8 ("clk: vc5: Enable addition output configurations of the Versaclock")

Suggested-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Adam Ford <aford173@...il.com>
Reviewed-by: Luca Ceresoli <luca@...aceresoli.net>
---
V3:   Fix spelling error, and use the style of checking (!variable) instead of
      (variable == NULL)

V2:   Fix an issue where a goto was going to use an unitialized variable.

diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c
index 9a5fb3834b9a..9a37168c4afc 100644
--- a/drivers/clk/clk-versaclock5.c
+++ b/drivers/clk/clk-versaclock5.c
@@ -789,10 +789,13 @@ static int vc5_get_output_config(struct i2c_client *client,
 	int ret = 0;
 
 	child_name = kasprintf(GFP_KERNEL, "OUT%d", clk_out->num + 1);
+	if (!child_name)
+		return -ENOMEM;
+
 	np_output = of_get_child_by_name(client->dev.of_node, child_name);
 	kfree(child_name);
 	if (!np_output)
-		goto output_done;
+		return 0;
 
 	ret = vc5_update_mode(np_output, clk_out);
 	if (ret)
@@ -813,7 +816,6 @@ static int vc5_get_output_config(struct i2c_client *client,
 
 	of_node_put(np_output);
 
-output_done:
 	return ret;
 }
 
@@ -828,7 +830,7 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	int ret;
 
 	vc5 = devm_kzalloc(&client->dev, sizeof(*vc5), GFP_KERNEL);
-	if (vc5 == NULL)
+	if (!vc5)
 		return -ENOMEM;
 
 	i2c_set_clientdata(client, vc5);
-- 
2.17.1