linux-kernel - [PATCH AUTOSEL for 4.9 065/156] afs: Fix page leak in afs_write

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Date:   Thu, 7 Dec 2017 15:49:11 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     David Howells <dhowells@...hat.com>, alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.9 065/156] afs: Fix page leak in
 afs_write_begin()

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>
---
 fs/afs/write.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/fs/afs/write.c b/fs/afs/write.c
index 4ab108e6a3cd..f9e5994e80ab 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -148,12 +148,12 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 		kfree(candidate);
 		return -ENOMEM;
 	}
-	*pagep = page;
-	/* page won't leak in error case: it eventually gets cleaned off LRU */
 
 	if (!PageUptodate(page) && len != PAGE_SIZE) {
 		ret = afs_fill_page(vnode, key, index << PAGE_SHIFT, page);
 		if (ret < 0) {
+			unlock_page(page);
+			put_page(page);
 			kfree(candidate);
 			_leave(" = %d [prep]", ret);
 			return ret;
@@ -161,6 +161,9 @@ int afs_write_begin(struct file *file, struct address_space *mapping,
 		SetPageUptodate(page);
 	}
 
+	/* page won't leak in error case: it eventually gets cleaned off LRU */
+	*pagep = page;
+
 try_again:
 	spin_lock(&vnode->writeback_lock);
 
-- 
2.11.0