[PATCH (resend)] fs: Fix dentry leak at dentry_open().

[PATCH (resend)] fs: Fix dentry leak at dentry_open().

[Tetsuo Handa]

>From fa9c553a609cd2aa6703d733ced5e727896ac176 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Thu, 16 Sep 2010 18:37:42 +0900
Subject: [PATCH] fs: Fix dentry leak at dentry_open().

dentry_open() says that it will have done dput(dentry) and mntput(mnt)
if it returns an error. But it was not calling dput(dentry) when mnt == NULL.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 fs/open.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index d74e198..501fda2 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -815,6 +815,7 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 	if (!mnt) {
 		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
 		dump_stack();
+		dput(dentry);
 		return ERR_PTR(-EINVAL);
 	}
 
-- 
1.7.1

Re: [PATCH (resend)] fs: Fix dentry leak at dentry_open().

[Al Viro]

On Wed, Jan 19, 2011 at 09:42:22AM +0900, Tetsuo Handa wrote:
> >From fa9c553a609cd2aa6703d733ced5e727896ac176 Mon Sep 17 00:00:00 2001
> From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> Date: Thu, 16 Sep 2010 18:37:42 +0900
> Subject: [PATCH] fs: Fix dentry leak at dentry_open().
> 
> dentry_open() says that it will have done dput(dentry) and mntput(mnt)
> if it returns an error. But it was not calling dput(dentry) when mnt == NULL.

NAK.  Turn that into BUG_ON(!mnt) and be done with that.

Re: [PATCH (resend)] fs: Fix dentry leak at dentry_open().

[Tetsuo Handa]

Al Viro wrote:
> NAK.  Turn that into BUG_ON(!mnt) and be done with that.

I see. Here is the updated patch.
----------------------------------------
>From b2618c1cf48cd817f5d0d10816e161282870ef46 Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Tue, 18 Jan 2011 23:05:39 +0900
Subject: [PATCH] fs: Use BUG_ON(!mnt) at dentry_open().

dentry_open() requires callers to pass a valid vfsmount.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
---
 fs/open.c |   13 ++-----------
 1 files changed, 2 insertions(+), 11 deletions(-)

diff --git a/fs/open.c b/fs/open.c
index e52389e..137ab87 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -811,17 +811,8 @@ struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags,
 
 	validate_creds(cred);
 
-	/*
-	 * We must always pass in a valid mount pointer.   Historically
-	 * callers got away with not passing it, but we must enforce this at
-	 * the earliest possible point now to avoid strange problems deep in the
-	 * filesystem stack.
-	 */
-	if (!mnt) {
-		printk(KERN_WARNING "%s called with NULL vfsmount\n", __func__);
-		dump_stack();
-		return ERR_PTR(-EINVAL);
-	}
+	/* We must always pass in a valid mount pointer. */
+	BUG_ON(!mnt);
 
 	error = -ENFILE;
 	f = get_empty_filp();
-- 
1.6.1