linux-kernel - [PATCH 4/9] drivers/xen/gntalloc.c: introduce missing kfree

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Message-Id: <1324661974-17281-4-git-send-email-julia@diku.dk>
Date:	Fri, 23 Dec 2011 18:39:29 +0100
From:	Julia Lawall <julia@...u.dk>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Cc:	kernel-janitors@...r.kernel.org,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	xen-devel@...ts.xensource.com,
	virtualization@...ts.linux-foundation.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH 4/9] drivers/xen/gntalloc.c: introduce missing kfree

Error handling code following a kmalloc should free the allocated data.
Out_unlock is used on both success and failure, so free vm_priv before
jumping to that label.

A simplified version of the semantic match that finds the problem is as
follows: (http://coccinelle.lip6.fr)

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

x@p1 = \(kmalloc\|kzalloc\|kcalloc\)(...);
...
if (x == NULL) S
<... when != x
     when != if (...) { <+...x...+> }
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/xen/gntalloc.c |    1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/xen/gntalloc.c b/drivers/xen/gntalloc.c
index e2400c8..934985d 100644
--- a/drivers/xen/gntalloc.c
+++ b/drivers/xen/gntalloc.c
@@ -525,6 +525,7 @@ static int gntalloc_mmap(struct file *filp, struct vm_area_struct *vma)
 		rv = -ENOENT;
 		pr_debug("%s: Could not find grant reference",
 				__func__);
+		kfree(vm_priv);
 		goto out_unlock;
 	}
 

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