linux-kernel - [PATCH 23/27] afs: Fix page leak in afs_write

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Message-ID: <148908590776.16794.7230863874143141245.stgit@warthog.procyon.org.uk>
Date:   Thu, 09 Mar 2017 18:58:27 +0000
From:   David Howells <dhowells@...hat.com>
To:     viro@...IV.linux.org.uk
Cc:     dhowells@...hat.com, linux-fsdevel@...r.kernel.org,
        linux-afs@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH 23/27] afs: Fix page leak in afs_write_begin()

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>
---

 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 f1450ea09406..6e13e96c3db0 100644
--- a/fs/afs/write.c
+++ b/fs/afs/write.c
@@ -154,12 +154,12 @@ 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, pos & PAGE_MASK, PAGE_SIZE, page);
 		if (ret < 0) {
+			unlock_page(page);
+			put_page(page);
 			kfree(candidate);
 			_leave(" = %d [prep]", ret);
 			return ret;
@@ -167,6 +167,9 @@ 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);