[PATCH] ecryptfs: Fix refcnt leak on ecryptfs_follow_link() error path

[PATCH] ecryptfs: Fix refcnt leak on ecryptfs_follow_link() error path

[OGAWA Hirofumi]

If ->follow_link handler return the error, it should decrement
nd->path refcnt. But, ecryptfs_follow_link() doesn't decrement.

This patch fix it by using usual nd_set_link() style error handling,
instead of playing with nd->path.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---

 fs/ecryptfs/inode.c |   19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff -puN fs/ecryptfs/inode.c~namei-ecryptfs-follow_link-fix fs/ecryptfs/inode.c
--- linux-2.6/fs/ecryptfs/inode.c~namei-ecryptfs-follow_link-fix	2010-01-12 00:15:10.000000000 +0900
+++ linux-2.6-hirofumi/fs/ecryptfs/inode.c	2010-01-12 00:15:10.000000000 +0900
@@ -715,7 +715,7 @@ static void *ecryptfs_follow_link(struct
 	/* Released in ecryptfs_put_link(); only release here on error */
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf) {
-		rc = -ENOMEM;
+		buf = ERR_PTR(-ENOMEM);
 		goto out;
 	}
 	old_fs = get_fs();
@@ -723,23 +723,22 @@ static void *ecryptfs_follow_link(struct
 	rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
 	set_fs(old_fs);
 	if (rc < 0)
-		goto out_free;
+		buf = ERR_PTR(rc);
 	else
 		buf[rc] = '\0';
-	rc = 0;
-	nd_set_link(nd, buf);
-	goto out;
-out_free:
-	kfree(buf);
 out:
-	return ERR_PTR(rc);
+	nd_set_link(nd, buf);
+	return NULL;
 }
 
 static void
 ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
 {
-	/* Free the char* */
-	kfree(nd_get_link(nd));
+	char *buf = nd_get_link(nd);
+	if (!IS_ERR(buf)) {
+		/* Free the char* */
+		kfree(buf);
+	}
 }
 
 /**
_

-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

Re: [PATCH] ecryptfs: Fix refcnt leak on ecryptfs_follow_link() error path

[Al Viro]

On Tue, Jan 12, 2010 at 03:36:14AM +0900, OGAWA Hirofumi wrote:
> 
> If ->follow_link handler return the error, it should decrement
> nd->path refcnt. But, ecryptfs_follow_link() doesn't decrement.
> 
> This patch fix it by using usual nd_set_link() style error handling,
> instead of playing with nd->path.

Applied.

Re: [PATCH] ecryptfs: Fix refcnt leak on ecryptfs_follow_link() error path

[OGAWA Hirofumi]

Al Viro <viro@ZenIV.linux.org.uk> writes:

> On Tue, Jan 12, 2010 at 03:36:14AM +0900, OGAWA Hirofumi wrote:
>> 
>> If ->follow_link handler return the error, it should decrement
>> nd->path refcnt. But, ecryptfs_follow_link() doesn't decrement.
>> 
>> This patch fix it by using usual nd_set_link() style error handling,
>> instead of playing with nd->path.
>
> Applied.

Sigh, sorry. I introduced new bug by this patch. Please apply this too.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>


[PATCH] ecryptfs: Fix memory leak of buf in ecryptfs_follow_link()

Fix memory leak of buf in ecryptfs_follow_link() in recent my change.

Signed-off-by: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
---

 fs/ecryptfs/inode.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff -puN fs/ecryptfs/inode.c~namei-ecryptfs-follow_link-fix-fix fs/ecryptfs/inode.c
--- linux-2.6/fs/ecryptfs/inode.c~namei-ecryptfs-follow_link-fix-fix	2010-01-14 05:33:49.000000000 +0900
+++ linux-2.6-hirofumi/fs/ecryptfs/inode.c	2010-01-14 05:34:30.000000000 +0900
@@ -722,9 +722,10 @@ static void *ecryptfs_follow_link(struct
 	set_fs(get_ds());
 	rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
 	set_fs(old_fs);
-	if (rc < 0)
+	if (rc < 0) {
+		kfree(buf);
 		buf = ERR_PTR(rc);
-	else
+	} else
 		buf[rc] = '\0';
 out:
 	nd_set_link(nd, buf);
_

Re: [PATCH] ecryptfs: Fix refcnt leak on ecryptfs_follow_link() error path

[Al Viro]

On Thu, Jan 14, 2010 at 12:32:13PM +0900, OGAWA Hirofumi wrote:
> Al Viro <viro@ZenIV.linux.org.uk> writes:
> 
> > On Tue, Jan 12, 2010 at 03:36:14AM +0900, OGAWA Hirofumi wrote:
> >> 
> >> If ->follow_link handler return the error, it should decrement
> >> nd->path refcnt. But, ecryptfs_follow_link() doesn't decrement.
> >> 
> >> This patch fix it by using usual nd_set_link() style error handling,
> >> instead of playing with nd->path.
> >
> > Applied.
> 
> Sigh, sorry. I introduced new bug by this patch. Please apply this too.

I'll fold it.  BTW, while we are at it, there's a leak in configfs/symlink.c
get_target() as well ;-/