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From: Julia Lawall <julia@diku.dk>
To: Chris Mason <chris.mason@oracle.com>,
	linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: [PATCH 3/5] fs/btrfs: Eliminate memory leak
Date: Tue, 24 Aug 2010 16:39:12 +0200 (CEST)	[thread overview]
Message-ID: <Pine.LNX.4.64.1008241638560.15172@ask.diku.dk> (raw)

From: Julia Lawall <julia@diku.dk>

This code is preceded by a call to btrfs_alloc_path, which allocates some
memory.  There is some error handling code at the end of the function that
frees it, that can be taken advantage of with a little ordering adjustment.

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

// <smpl>
@r exists@
local idexpression x;
expression E;
identifier f1;
iterator I;
@@

x = btrfs_alloc_path(...);
<... when != x
     when != true (x == NULL || ...)
     when != if (...) { <+...x...+> }
     when != I (...) { <+...x...+> }
(
 x == NULL
|
 x == E
|
 x->f1
)
...>
* return ...;
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 fs/btrfs/inode.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c038644..d38587c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4438,15 +4438,14 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	BUG_ON(!path);
 
 	inode = new_inode(root->fs_info->sb);
-	if (!inode)
-		return ERR_PTR(-ENOMEM);
-
+	if (!inode) {
+		ret = -ENOMEM;
+		goto fail_path;
+	}
 	if (dir) {
 		ret = btrfs_set_inode_index(dir, index);
-		if (ret) {
-			iput(inode);
-			return ERR_PTR(ret);
-		}
+		if (ret)
+			goto fail_inode;
 	}
 	/*
 	 * index_cnt is ignored for everything but a dir,
@@ -4519,8 +4518,10 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 fail:
 	if (dir)
 		BTRFS_I(dir)->index_cnt--;
-	btrfs_free_path(path);
+fail_inode:
 	iput(inode);
+fail_path:
+	btrfs_free_path(path);
 	return ERR_PTR(ret);
 }
 

WARNING: multiple messages have this Message-ID (diff)
From: Julia Lawall <julia@diku.dk>
To: Chris Mason <chris.mason@oracle.com>,
	linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
	kernel-janitors@vger.kernel.org
Subject: [PATCH 3/5] fs/btrfs: Eliminate memory leak
Date: Tue, 24 Aug 2010 14:39:12 +0000	[thread overview]
Message-ID: <Pine.LNX.4.64.1008241638560.15172@ask.diku.dk> (raw)

From: Julia Lawall <julia@diku.dk>

This code is preceded by a call to btrfs_alloc_path, which allocates some
memory.  There is some error handling code at the end of the function that
frees it, that can be taken advantage of with a little ordering adjustment.

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

// <smpl>
@r exists@
local idexpression x;
expression E;
identifier f1;
iterator I;
@@

x = btrfs_alloc_path(...);
<... when != x
     when != true (x = NULL || ...)
     when != if (...) { <+...x...+> }
     when != I (...) { <+...x...+> }
(
 x = NULL
|
 x = E
|
 x->f1
)
...>
* return ...;
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>

---
 fs/btrfs/inode.c |   17 +++++++++--------
 1 file changed, 9 insertions(+), 8 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index c038644..d38587c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4438,15 +4438,14 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 	BUG_ON(!path);
 
 	inode = new_inode(root->fs_info->sb);
-	if (!inode)
-		return ERR_PTR(-ENOMEM);
-
+	if (!inode) {
+		ret = -ENOMEM;
+		goto fail_path;
+	}
 	if (dir) {
 		ret = btrfs_set_inode_index(dir, index);
-		if (ret) {
-			iput(inode);
-			return ERR_PTR(ret);
-		}
+		if (ret)
+			goto fail_inode;
 	}
 	/*
 	 * index_cnt is ignored for everything but a dir,
@@ -4519,8 +4518,10 @@ static struct inode *btrfs_new_inode(struct btrfs_trans_handle *trans,
 fail:
 	if (dir)
 		BTRFS_I(dir)->index_cnt--;
-	btrfs_free_path(path);
+fail_inode:
 	iput(inode);
+fail_path:
+	btrfs_free_path(path);
 	return ERR_PTR(ret);
 }
 

             reply	other threads:[~2010-08-24 14:39 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-08-24 14:39 Julia Lawall [this message]
2010-08-24 14:39 ` [PATCH 3/5] fs/btrfs: Eliminate memory leak Julia Lawall
     [not found] <1282776100-21671-1-git-send-email-julia@diku.dk>
     [not found] ` <1282776100-21671-4-git-send-email-julia@diku.dk>
2010-08-25 21:57   ` Julia Lawall

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