From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Jeffery Subject: [PATCH] scsi: memory leak with 1MB tape I/O Date: Wed, 11 Apr 2012 12:14:25 -0400 Message-ID: <4F85ADE1.30803@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from mail-gx0-f174.google.com ([209.85.161.174]:34779 "EHLO mail-gx0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759525Ab2DKQCn (ORCPT ); Wed, 11 Apr 2012 12:02:43 -0400 Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org There is a memory leak in the st driver when sending large enough reads or writes using st's direct I/O path. As part of mapping the application's memory, a buffer to hold page pointers is allocated and the count of mapped pages is stored in field do_dio. A non-zero do_dio marks that direct I/O is in use. But do_dio is only 1 byte in size. Mapping 256 4k pages overflows do_dio and causes it to be set to 0, like direct I/O option was not used. When the I/O completes, the buffer to hold the page pointers is not freed, and the page counts of the mapped pages are not reduced. Every I/O of this size then leaks memory. The size of do_dio needs to be increased to prevent it wrapping around. signed-off-by: David Jeffery --- --- a/drivers/scsi/st.h 2012-04-10 13:21:30.000000000 -0400 +++ b/drivers/scsi/st.h 2012-04-10 14:55:43.000000000 -0400 @@ -35,8 +35,8 @@ /* The tape buffer descriptor. */ struct st_buffer { unsigned char dma; /* DMA-able buffer */ - unsigned char do_dio; /* direct i/o set up? */ unsigned char cleared; /* internal buffer cleared after open? */ + unsigned short do_dio; /* direct i/o set up? */ int buffer_size; int buffer_blocks; int buffer_bytes;