linux-kernel - Re: [PATCH 6/10] drivers/net/wireless/iwlwifi: introduce missing kfree

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Date:	Mon, 3 Aug 2009 11:11:45 +0200 (CEST)
From:	Julia Lawall <julia@...u.dk>
To:	Zhu Yi <yi.zhu@...el.com>
Cc:	"Chatre, Reinette" <reinette.chatre@...el.com>,
	"linux-wireless@...r.kernel.org" <linux-wireless@...r.kernel.org>,
	"ipw3945-devel@...ts.sourceforge.net" 
	<ipw3945-devel@...ts.sourceforge.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH 6/10] drivers/net/wireless/iwlwifi: introduce missing
 kfree

From: Julia Lawall <julia@...u.dk>

Move orthogonal error handling code up before a kzalloc, so that it 
doesn't have to free the allocated data.

The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@r exists@
local idexpression x;
statement S;
expression E;
identifier f,f1,l;
position p1,p2;
expression *ptr != NULL;
@@

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
(
x->f1 = E
|
 (x->f1 == NULL || ...)
|
 f(...,x->f1,...)
)
...>
(
 return \(0\|<+...x...+>\|ptr\);
|
 return@p2 ...;
)

@script:python@
p1 << r.p1;
p2 << r.p2;
@@

print "* file: %s kmalloc %s return %s" % (p1[0].file,p1[0].line,p2[0].line)
// </smpl>

Signed-off-by: Julia Lawall <julia@...u.dk>
---
 drivers/net/wireless/iwlwifi/iwl-debugfs.c     |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/iwlwifi/iwl-debugfs.c b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
index 7707a26..6748a3f 100644
--- a/drivers/net/wireless/iwlwifi/iwl-debugfs.c
+++ b/drivers/net/wireless/iwlwifi/iwl-debugfs.c
@@ -310,18 +310,18 @@ static ssize_t iwl_dbgfs_nvm_read(struct file *file,
 		return -ENODATA;
 	}
 
+	ptr = priv->eeprom;
+	if (!ptr) {
+		IWL_ERR(priv, "Invalid EEPROM/OTP memory\n");
+		return -ENOMEM;
+	}
+
 	/* 4 characters for byte 0xYY */
 	buf = kzalloc(buf_size, GFP_KERNEL);
 	if (!buf) {
 		IWL_ERR(priv, "Can not allocate Buffer\n");
 		return -ENOMEM;
 	}
-
-	ptr = priv->eeprom;
-	if (!ptr) {
-		IWL_ERR(priv, "Invalid EEPROM/OTP memory\n");
-		return -ENOMEM;
-	}
 	pos += scnprintf(buf + pos, buf_size - pos, "NVM Type: %s\n",
 			(priv->nvm_device_type == NVM_DEVICE_TYPE_OTP)
 			? "OTP" : "EEPROM");
--
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