cifs: Check for existing directory when opening file with O_CREAT
authorSachin Prabhu <sprabhu@redhat.com>
Thu, 7 Jul 2016 20:28:27 +0000 (21:28 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 20 Aug 2016 16:09:20 +0000 (18:09 +0200)
commit 8d9535b6efd86e6c07da59f97e68f44efb7fe080 upstream.

When opening a file with O_CREAT flag, check to see if the file opened
is an existing directory.

This prevents the directory from being opened which subsequently causes
a crash when the close function for directories cifs_closedir() is called
which frees up the file->private_data memory while the file is still
listed on the open file list for the tcon.

Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reported-by: Xiaoli Feng <xifeng@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
fs/cifs/dir.c

index b95bffcee8aa05df96ef9fac8ab2c0fef2d5d741..26a3b389a265b7bb5eac182b51a5bfbedb14e114 100644 (file)
@@ -245,6 +245,13 @@ cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
                                goto cifs_create_get_file_info;
                        }
 
+                       if (S_ISDIR(newinode->i_mode)) {
+                               CIFSSMBClose(xid, tcon, fid->netfid);
+                               iput(newinode);
+                               rc = -EISDIR;
+                               goto out;
+                       }
+
                        if (!S_ISREG(newinode->i_mode)) {
                                /*
                                 * The server may allow us to open things like
@@ -415,10 +422,14 @@ cifs_create_set_dentry:
        if (rc != 0) {
                cifs_dbg(FYI, "Create worked, get_inode_info failed rc = %d\n",
                         rc);
-               if (server->ops->close)
-                       server->ops->close(xid, tcon, fid);
-               goto out;
+               goto out_err;
        }
+
+       if (S_ISDIR(newinode->i_mode)) {
+               rc = -EISDIR;
+               goto out_err;
+       }
+
        d_drop(direntry);
        d_add(direntry, newinode);
 
@@ -426,6 +437,13 @@ out:
        kfree(buf);
        kfree(full_path);
        return rc;
+
+out_err:
+       if (server->ops->close)
+               server->ops->close(xid, tcon, fid);
+       if (newinode)
+               iput(newinode);
+       goto out;
 }
 
 int