From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Stefan Hajnoczi , "Michael S. Tsirkin" , Asias He , Nicholas Bellinger Subject: [PATCH 3.10 32/74] vhost/scsi: Fix incorrect usage of get_user_pages_fast write parameter Date: Fri, 8 Nov 2013 22:51:37 -0800 Message-Id: <20131109065115.774268642@linuxfoundation.org> In-Reply-To: <20131109065113.502217951@linuxfoundation.org> References: <20131109065113.502217951@linuxfoundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nicholas Bellinger commit 60a01f558af9c48b0bb31f303c479e32721add3f upstream. This patch addresses a long-standing bug where the get_user_pages_fast() write parameter used for setting the underlying page table entry permission bits was incorrectly set to write=1 for data_direction=DMA_TO_DEVICE, and passed into get_user_pages_fast() via vhost_scsi_map_iov_to_sgl(). However, this parameter is intended to signal WRITEs to pinned userspace PTEs for the virtio-scsi DMA_FROM_DEVICE -> READ payload case, and *not* for the virtio-scsi DMA_TO_DEVICE -> WRITE payload case. This bug would manifest itself as random process segmentation faults on KVM host after repeated vhost starts + stops and/or with lots of vhost endpoints + LUNs. Cc: Stefan Hajnoczi Cc: Michael S. Tsirkin Cc: Asias He Signed-off-by: Nicholas Bellinger Signed-off-by: Greg Kroah-Hartman --- drivers/vhost/scsi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -1017,7 +1017,7 @@ static void vhost_scsi_handle_vq(struct if (data_direction != DMA_NONE) { ret = vhost_scsi_map_iov_to_sgl(tv_cmd, &vq->iov[data_first], data_num, - data_direction == DMA_TO_DEVICE); + data_direction == DMA_FROM_DEVICE); if (unlikely(ret)) { vq_err(vq, "Failed to map iov to sgl\n"); goto err_free;