linux-kernel - [PATCH 3.18 32/69] afs: Fix page leak in afs_write

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Date:   Mon, 18 Dec 2017 16:48:18 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Howells <dhowells@...hat.com>,
        Sasha Levin <alexander.levin@...izon.com>
Subject: [PATCH 3.18 32/69] afs: Fix page leak in afs_write_begin()

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: David Howells <dhowells@...hat.com>


[ Upstream commit 6d06b0d25209c80e99c1e89700f1e09694a3766b ]

afs_write_begin() leaks a ref and a lock on a page if afs_fill_page()
fails.  Fix the leak by unlocking and releasing the page in the error path.

Signed-off-by: David Howells <dhowells@...hat.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/afs/write.c |    7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -149,12 +149,12 @@ int afs_write_begin(struct file *file, s
 		kfree(candidate);
 		return -ENOMEM;
 	}
-	*pagep = page;
-	/* page won't leak in error case: it eventually gets cleaned off LRU */
 
 	if (!PageUptodate(page) && len != PAGE_CACHE_SIZE) {
 		ret = afs_fill_page(vnode, key, index << PAGE_CACHE_SHIFT, page);
 		if (ret < 0) {
+			unlock_page(page);
+			put_page(page);
 			kfree(candidate);
 			_leave(" = %d [prep]", ret);
 			return ret;
@@ -162,6 +162,9 @@ int afs_write_begin(struct file *file, s
 		SetPageUptodate(page);
 	}
 
+	/* page won't leak in error case: it eventually gets cleaned off LRU */
+	*pagep = page;
+
 try_again:
 	spin_lock(&vnode->writeback_lock);