befs: Validate length of long symbolic links, CVE-2011-2928

[linux-flexiantxendom0-natty.git] / fs / befs / linuxvfs.c

diff --git a/fs/befs/linuxvfs.c b/fs/befs/linuxvfs.c
index aa4e7c7..e8ff0d7 100644 (file)
--- a/fs/befs/linuxvfs.c
+++ b/fs/befs/linuxvfs.c
@@ -284,12 +284,18 @@ befs_alloc_inode(struct super_block *sb)
         return &bi->vfs_inode;
 }
 
-static void
-befs_destroy_inode(struct inode *inode)
+static void befs_i_callback(struct rcu_head *head)
 {
+       struct inode *inode = container_of(head, struct inode, i_rcu);
+       INIT_LIST_HEAD(&inode->i_dentry);
         kmem_cache_free(befs_inode_cachep, BEFS_I(inode));
 }
 
+static void befs_destroy_inode(struct inode *inode)
+{
+       call_rcu(&inode->i_rcu, befs_i_callback);
+}
+
 static void init_once(void *foo)
 {
         struct befs_inode_info *bi = (struct befs_inode_info *) foo;
@@ -384,7 +390,7 @@ static struct inode *befs_iget(struct super_block *sb, unsigned long ino)
                int num_blks;
 
                befs_ino->i_data.ds =
-                   fsds_to_cpu(sb, raw_inode->data.datastream);
+                   fsds_to_cpu(sb, &raw_inode->data.datastream);
 
                num_blks = befs_count_blocks(sb, &befs_ino->i_data.ds);
                inode->i_blocks =
@@ -469,17 +475,22 @@ befs_follow_link(struct dentry *dentry, struct nameidata *nd)
                befs_data_stream *data = &befs_ino->i_data.ds;
                befs_off_t len = data->size;
 
-               befs_debug(sb, "Follow long symlink");
-
-               link = kmalloc(len, GFP_NOFS);
-               if (!link) {
-                       link = ERR_PTR(-ENOMEM);
-               } else if (befs_read_lsymlink(sb, data, link, len) != len) {
-                       kfree(link);
-                       befs_error(sb, "Failed to read entire long symlink");
+               if (len == 0) {
+                       befs_error(sb, "Long symlink with illegal length");
                        link = ERR_PTR(-EIO);
                } else {
-                       link[len - 1] = '\0';
+                       befs_debug(sb, "Follow long symlink");
+
+                       link = kmalloc(len, GFP_NOFS);
+                       if (!link) {
+                               link = ERR_PTR(-ENOMEM);
+                       } else if (befs_read_lsymlink(sb, data, link, len) != len) {
+                               kfree(link);
+                               befs_error(sb, "Failed to read entire long symlink");
+                               link = ERR_PTR(-EIO);
+                       } else {
+                               link[len - 1] = '\0';
+                       }
                }
        } else {
                link = befs_ino->i_data.symlink;