linux-kernel - [PATCH] mfd: menelaus: remove null pointer dereference

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Message-ID: <20140809164027.GA20561@himangi-Dell>
Date:	Sat, 9 Aug 2014 22:10:27 +0530
From:	Himangi Saraogi <himangi774@...il.com>
To:	Samuel Ortiz <sameo@...ux.intel.com>,
	Lee Jones <lee.jones@...aro.org>, linux-kernel@...r.kernel.org
Cc:	Julia Lawall <julia.lawall@...6.fr>
Subject: [PATCH] mfd: menelaus: remove null pointer dereference

If vtg is NULL, it is not possible to access its mode_reg field. At all
sites where the static function menelaus_set_voltage is called, the first
argument is the address of a structure defined in the file. So, the null
test is unnecessary and is removed. Also, a label is done away with.

This problem was found using the following Coccinelle semantic match:

// <smpl>
@@
expression E, E1;
identifier f;
statement S1,S2,S3;
@@

* if (E == NULL)
{
  ... when != if (E == NULL) S1 else S2
      when != E = E1
* E->f
  ... when any
  return ...;
}
else S3
// </smpl>

Signed-off-by: Himangi Saraogi <himangi774@...il.com>
Acked-by: Julia Lawall <julia.lawall@...6.fr>
---
Not compile tested.
 drivers/mfd/menelaus.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/drivers/mfd/menelaus.c b/drivers/mfd/menelaus.c
index 5e2667a..18ff56f 100644
--- a/drivers/mfd/menelaus.c
+++ b/drivers/mfd/menelaus.c
@@ -466,8 +466,6 @@ static int menelaus_set_voltage(const struct menelaus_vtg *vtg, int mV,
 	struct i2c_client *c = the_menelaus->client;
 
 	mutex_lock(&the_menelaus->lock);
-	if (!vtg)
-		goto set_voltage;
 
 	ret = menelaus_read_reg(vtg->vtg_reg);
 	if (ret < 0)
@@ -482,7 +480,6 @@ static int menelaus_set_voltage(const struct menelaus_vtg *vtg, int mV,
 	ret = menelaus_write_reg(vtg->vtg_reg, val);
 	if (ret < 0)
 		goto out;
-set_voltage:
 	ret = menelaus_write_reg(vtg->mode_reg, mode);
 out:
 	mutex_unlock(&the_menelaus->lock);
-- 
1.9.1

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