hfs: fix memory leak when unmounting

When an HFS filesystem is unmounted, it leaks a 2-page bitmap.  Also,
under extreme memory pressure, it's possible that hfs_releasepage() may
use a tree pointer that has not been initialized, and if so, the release
request should just be rejected.

[akpm@linux-foundation.org: free_pages(0) is legal, remove obvious comment]
Signed-off-by: Dave Anderson <anderson@redhat.com>
Tested-by: Eugene Teo <eugeneteo@kernel.sg>
Cc: Roman Zippel <zippel@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
index 9435dda8f1e0..a1cbff2b4d99 100644
--- a/fs/hfs/inode.c
+++ b/fs/hfs/inode.c
@@ -70,6 +70,10 @@ static int hfs_releasepage(struct page *page, gfp_t mask)
                 BUG();
                 return 0;
         }
+
+        if (!tree)
+                return 0;
+
         if (tree->node_size >= PAGE_CACHE_SIZE) {
                 nidx = page->index >> (tree->node_size_shift - PAGE_CACHE_SHIFT);
                 spin_lock(&tree->hash_lock);