[PATCH] clk: vc5: Fix use after free in vc5_probe

[trix]

From: Tom Rix <trix@xxxxxxxxxx>

clang static analysis reports this error

clk-versaclock5.c:887:3: warning: Use of memory after it is freed
  [unix.Malloc]
      dev_err(&client->dev, "unable to register %s\n", init.name);
      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

A representative problem block of code is

ret = devm_clk_hw_register(&client->dev, &vc5->clk_mux);
kfree(init.name);	/* clock framework made a copy of the name */
if (ret) {
	dev_err(&client->dev, "unable to register %s\n", init.name);
	goto err_clk;
}

init.name is freed and then used.

So reorder the free.

Fixes: f491276a5168 ("clk: vc5: Allow Versaclock driver to support multiple instances")

Signed-off-by: Tom Rix <trix@xxxxxxxxxx>
---
 drivers/clk/clk-versaclock5.c | 21 ++++++++++++++-------
 1 file changed, 14 insertions(+), 7 deletions(-)

diff --git a/drivers/clk/clk-versaclock5.c b/drivers/clk/clk-versaclock5.c
index 9a5fb3834b9a..72c9ae460a01 100644
--- a/drivers/clk/clk-versaclock5.c
+++ b/drivers/clk/clk-versaclock5.c
@@ -882,11 +882,12 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	init.parent_names = parent_names;
 	vc5->clk_mux.init = &init;
 	ret = devm_clk_hw_register(&client->dev, &vc5->clk_mux);
-	kfree(init.name);	/* clock framework made a copy of the name */
 	if (ret) {
 		dev_err(&client->dev, "unable to register %s\n", init.name);
+		kfree(init.name);
 		goto err_clk;
 	}
+	kfree(init.name);	/* clock framework made a copy of the name */
 
 	if (vc5->chip_info->flags & VC5_HAS_PFD_FREQ_DBL) {
 		/* Register frequency doubler */
@@ -900,12 +901,13 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		init.num_parents = 1;
 		vc5->clk_mul.init = &init;
 		ret = devm_clk_hw_register(&client->dev, &vc5->clk_mul);
-		kfree(init.name); /* clock framework made a copy of the name */
 		if (ret) {
 			dev_err(&client->dev, "unable to register %s\n",
 				init.name);
+			kfree(init.name);
 			goto err_clk;
 		}
+		kfree(init.name); /* clock framework made a copy of the name */
 	}
 
 	/* Register PFD */
@@ -921,11 +923,12 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	init.num_parents = 1;
 	vc5->clk_pfd.init = &init;
 	ret = devm_clk_hw_register(&client->dev, &vc5->clk_pfd);
-	kfree(init.name);	/* clock framework made a copy of the name */
 	if (ret) {
 		dev_err(&client->dev, "unable to register %s\n", init.name);
+		kfree(init.name);
 		goto err_clk;
 	}
+	kfree(init.name);	/* clock framework made a copy of the name */
 
 	/* Register PLL */
 	memset(&init, 0, sizeof(init));
@@ -939,11 +942,12 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	vc5->clk_pll.vc5 = vc5;
 	vc5->clk_pll.hw.init = &init;
 	ret = devm_clk_hw_register(&client->dev, &vc5->clk_pll.hw);
-	kfree(init.name); /* clock framework made a copy of the name */
 	if (ret) {
 		dev_err(&client->dev, "unable to register %s\n", init.name);
+		kfree(init.name);
 		goto err_clk;
 	}
+	kfree(init.name); /* clock framework made a copy of the name */
 
 	/* Register FODs */
 	for (n = 0; n < vc5->chip_info->clk_fod_cnt; n++) {
@@ -960,12 +964,13 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		vc5->clk_fod[n].vc5 = vc5;
 		vc5->clk_fod[n].hw.init = &init;
 		ret = devm_clk_hw_register(&client->dev, &vc5->clk_fod[n].hw);
-		kfree(init.name); /* clock framework made a copy of the name */
 		if (ret) {
 			dev_err(&client->dev, "unable to register %s\n",
 				init.name);
+			kfree(init.name);
 			goto err_clk;
 		}
+		kfree(init.name); /* clock framework made a copy of the name */
 	}
 
 	/* Register MUX-connected OUT0_I2C_SELB output */
@@ -981,11 +986,12 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	vc5->clk_out[0].vc5 = vc5;
 	vc5->clk_out[0].hw.init = &init;
 	ret = devm_clk_hw_register(&client->dev, &vc5->clk_out[0].hw);
-	kfree(init.name);	/* clock framework made a copy of the name */
 	if (ret) {
 		dev_err(&client->dev, "unable to register %s\n", init.name);
+		kfree(init.name);
 		goto err_clk;
 	}
+	kfree(init.name); /* clock framework made a copy of the name */
 
 	/* Register FOD-connected OUTx outputs */
 	for (n = 1; n < vc5->chip_info->clk_out_cnt; n++) {
@@ -1008,12 +1014,13 @@ static int vc5_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		vc5->clk_out[n].vc5 = vc5;
 		vc5->clk_out[n].hw.init = &init;
 		ret = devm_clk_hw_register(&client->dev, &vc5->clk_out[n].hw);
-		kfree(init.name); /* clock framework made a copy of the name */
 		if (ret) {
 			dev_err(&client->dev, "unable to register %s\n",
 				init.name);
+			kfree(init.name);
 			goto err_clk;
 		}
+		kfree(init.name); /* clock framework made a copy of the name */
 
 		/* Fetch Clock Output configuration from DT (if specified) */
 		ret = vc5_get_output_config(client, &vc5->clk_out[n]);
-- 
2.18.1