From 3020093f578fb6c9acc6914dfd887a1ebd1db659 Mon Sep 17 00:00:00 2001
From: Trond Myklebust <Trond.Myklebust@netapp.com>
Date: Sat, 20 Nov 2010 15:18:22 -0500
Subject: [PATCH] NFS: Correct the array bound calculation in
nfs_readdir_add_to_array
It looks as if the array size calculation in MAX_READDIR_ARRAY does not
take the alignment of struct nfs_cache_array_entry into account.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
---
fs/nfs/dir.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)
diff --git a/fs/nfs/dir.c b/fs/nfs/dir.c
index ddc2e439702b..ced7291cc5f8 100644
--- a/fs/nfs/dir.c
+++ b/fs/nfs/dir.c
@@ -171,8 +171,6 @@ struct nfs_cache_array {
struct nfs_cache_array_entry array[0];
};
-#define MAX_READDIR_ARRAY ((PAGE_SIZE - sizeof(struct nfs_cache_array)) / sizeof(struct nfs_cache_array_entry))
-
typedef __be32 * (*decode_dirent_t)(struct xdr_stream *, struct nfs_entry *, struct nfs_server *, int);
typedef struct {
struct file *file;
@@ -257,11 +255,14 @@ int nfs_readdir_add_to_array(struct nfs_entry *entry, struct page *page)
if (IS_ERR(array))
return PTR_ERR(array);
- ret = -ENOSPC;
- if (array->size >= MAX_READDIR_ARRAY)
- goto out;
cache_entry = &array->array[array->size];
+
+ /* Check that this entry lies within the page bounds */
+ ret = -ENOSPC;
+ if ((char *)&cache_entry[1] - (char *)page_address(page) > PAGE_SIZE)
+ goto out;
+
cache_entry->cookie = entry->prev_cookie;
cache_entry->ino = entry->ino;
ret = nfs_readdir_make_qstr(&cache_entry->string, entry->name, entry->len);