cifs: Check for existing directory when opening file with O_CREAT

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>
CC: Stable <stable@vger.kernel.org>
Reported-by: Xiaoli Feng <xifeng@redhat.com>

diff --git a/fs/cifs/dir.c b/fs/cifs/dir.c
index c3eb998..5089e42 100644 (file)
--- a/fs/cifs/dir.c
+++ b/fs/cifs/dir.c
@@ -229,6 +229,13 @@ 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
@@ -399,10 +406,14 @@ 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);
 
@@ -410,6 +421,13 @@ 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