linux-kernel - [PATCH v2] configfs: Fix config_item refcnt error in __configfs_open

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Message-Id: <20210311113510.1031406-1-gregkh@linuxfoundation.org>
Date:   Thu, 11 Mar 2021 12:35:10 +0100
From:   gregkh@...uxfoundation.org
To:     Christoph Hellwig <hch@....de>, Joel Becker <jlbec@...lplan.org>
Cc:     linux-kernel@...r.kernel.org, Al Viro <viro@...iv.linux.org.uk>,
        Daniel Rosenberg <drosen@...gle.com>, stable@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [PATCH v2] configfs: Fix config_item refcnt error in __configfs_open_file()

From: Daniel Rosenberg <drosen@...gle.com>

__configfs_open_file() used to use configfs_get_config_item, but changed
in commit b0841eefd969 ("configfs: provide exclusion between IO and
removals") to just call to_item. The error path still tries to clean up
the reference, incorrectly decrementing the ref count.

Signed-off-by: Daniel Rosenberg <drosen@...gle.com>
Cc: stable@...r.kernel.org
Fixes: b0841eefd969 ("configfs: provide exclusion between IO and removals")
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
v2: goto the correct out_ label as pointed out by Christoph

 fs/configfs/file.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/fs/configfs/file.c b/fs/configfs/file.c
index 1f0270229d7b..da8351d1e455 100644
--- a/fs/configfs/file.c
+++ b/fs/configfs/file.c
@@ -378,7 +378,7 @@ static int __configfs_open_file(struct inode *inode, struct file *file, int type
 
 	attr = to_attr(dentry);
 	if (!attr)
-		goto out_put_item;
+		goto out_free_buffer;
 
 	if (type & CONFIGFS_ITEM_BIN_ATTR) {
 		buffer->bin_attr = to_bin_attr(dentry);
@@ -391,7 +391,7 @@ static int __configfs_open_file(struct inode *inode, struct file *file, int type
 	/* Grab the module reference for this attribute if we have one */
 	error = -ENODEV;
 	if (!try_module_get(buffer->owner))
-		goto out_put_item;
+		goto out_free_buffer;
 
 	error = -EACCES;
 	if (!buffer->item->ci_type)
@@ -435,8 +435,6 @@ static int __configfs_open_file(struct inode *inode, struct file *file, int type
 
 out_put_module:
 	module_put(buffer->owner);
-out_put_item:
-	config_item_put(buffer->item);
 out_free_buffer:
 	up_read(&frag->frag_sem);
 	kfree(buffer);
-- 
2.30.2