From: Chris Mason <chris.mason@oracle.com>
Date: Mon, 22 Nov 2010 03:27:44 +0000 (-0500)
Subject: Btrfs: avoid NULL pointer deref in try_release_extent_buffer
X-Git-Tag: v2.6.37-rc4~6^2~8
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=45f49bce99d008d6864a20324548f35936ba46fb;p=linux.git

Btrfs: avoid NULL pointer deref in try_release_extent_buffer

If we fail to find a pointer in the radix tree, don't try
to deref the NULL one we do have.

Signed-off-by: Chris Mason <chris.mason@oracle.com>
---

diff --git a/fs/btrfs/extent_io.c b/fs/btrfs/extent_io.c
index f60aa3c35c23..143d3f541d64 100644
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -3837,8 +3837,10 @@ int try_release_extent_buffer(struct extent_io_tree *tree, struct page *page)
 
 	spin_lock(&tree->buffer_lock);
 	eb = radix_tree_lookup(&tree->buffer, start >> PAGE_CACHE_SHIFT);
-	if (!eb)
-		goto out;
+	if (!eb) {
+		spin_unlock(&tree->buffer_lock);
+		return ret;
+	}
 
 	if (test_bit(EXTENT_BUFFER_DIRTY, &eb->bflags)) {
 		ret = 0;