NFS: Fix memory leaks and corruption in readdir

commit 4b310319c6a8ce708f1033d57145e2aa027a883c upstream.

nfs_readdir_xdr_to_array() must not exit without having initialised
the array, so that the page cache deletion routines can safely
call nfs_readdir_clear_array().
Furthermore, we should ensure that if we exit nfs_readdir_filler()
with an error, we free up any page contents to prevent a leak
if we try to fill the page again.

Fixes: 11de3b11e08c ("NFS: Fix a memory leak in nfs_readdir")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
Reviewed-by: Benjamin Coddington <bcodding@redhat.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index 52694e2df3886339e67b1b396985d9b7dc93a53e..6458364eff1e560fd3f66a6fb5faf02cb23f5bff 100644 (file)
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -169,6 +169,17 @@ typedef struct {
        unsigned int    eof:1;
 } nfs_readdir_descriptor_t;
 
+static
+void nfs_readdir_init_array(struct page *page)
+{
+       struct nfs_cache_array *array;
+
+       array = kmap_atomic(page);
+       memset(array, 0, sizeof(struct nfs_cache_array));
+       array->eof_index = -1;
+       kunmap_atomic(array);
+}
+
 /*
  * we are freeing strings created by nfs_add_to_readdir_array()
  */
@@ -181,6 +192,7 @@ void nfs_readdir_clear_array(struct page *page)
        array = kmap_atomic(page);
        for (i = 0; i < array->size; i++)
                kfree(array->array[i].string.name);
+       array->size = 0;
        kunmap_atomic(array);
 }
 
@@ -580,6 +592,8 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
        int status = -ENOMEM;
        unsigned int array_size = ARRAY_SIZE(pages);
 
+       nfs_readdir_init_array(page);
+
        entry.prev_cookie = 0;
        entry.cookie = desc->last_cookie;
        entry.eof = 0;
@@ -596,8 +610,6 @@ int nfs_readdir_xdr_to_array(nfs_readdir_descriptor_t *desc, struct page *page,
        }
 
        array = kmap(page);
-       memset(array, 0, sizeof(struct nfs_cache_array));
-       array->eof_index = -1;
 
        status = nfs_readdir_large_page(pages, array_size);
        if (status < 0)
@@ -651,6 +663,7 @@ int nfs_readdir_filler(nfs_readdir_descriptor_t *desc, struct page* page)
        unlock_page(page);
        return 0;
  error:
+       nfs_readdir_clear_array(page);
        unlock_page(page);
        return ret;
 }