Commit 7fc35c75 authored by Oliver Neukum's avatar Oliver Neukum Committed by Greg Kroah-Hartman

UAS: fix alignment of scatter/gather segments

commit 3ae62a42 upstream.

This is the UAS version of

747668db
usb-storage: Set virt_boundary_mask to avoid SG overflows

We are not as likely to be vulnerable as storage, as it is unlikelier
that UAS is run over a controller without native support for SG,
but the issue exists.
The issue has been existing since the inception of the driver.

Fixes: 115bb1ff ("USB: Add UAS driver")
Signed-off-by: default avatarOliver Neukum <oneukum@suse.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d00686df
...@@ -789,24 +789,33 @@ static int uas_slave_alloc(struct scsi_device *sdev) ...@@ -789,24 +789,33 @@ static int uas_slave_alloc(struct scsi_device *sdev)
{ {
struct uas_dev_info *devinfo = struct uas_dev_info *devinfo =
(struct uas_dev_info *)sdev->host->hostdata; (struct uas_dev_info *)sdev->host->hostdata;
int maxp;
sdev->hostdata = devinfo; sdev->hostdata = devinfo;
/* /*
* USB has unusual DMA-alignment requirements: Although the * We have two requirements here. We must satisfy the requirements
* starting address of each scatter-gather element doesn't matter, * of the physical HC and the demands of the protocol, as we
* the length of each element except the last must be divisible * definitely want no additional memory allocation in this path
* by the Bulk maxpacket value. There's currently no way to * ruling out using bounce buffers.
* express this by block-layer constraints, so we'll cop out
* and simply require addresses to be aligned at 512-byte
* boundaries. This is okay since most block I/O involves
* hardware sectors that are multiples of 512 bytes in length,
* and since host controllers up through USB 2.0 have maxpacket
* values no larger than 512.
* *
* But it doesn't suffice for Wireless USB, where Bulk maxpacket * For a transmission on USB to continue we must never send
* values can be as large as 2048. To make that work properly * a package that is smaller than maxpacket. Hence the length of each
* will require changes to the block layer. * scatterlist element except the last must be divisible by the
* Bulk maxpacket value.
* If the HC does not ensure that through SG,
* the upper layer must do that. We must assume nothing
* about the capabilities off the HC, so we use the most
* pessimistic requirement.
*/
maxp = usb_maxpacket(devinfo->udev, devinfo->data_in_pipe, 0);
blk_queue_virt_boundary(sdev->request_queue, maxp - 1);
/*
* The protocol has no requirements on alignment in the strict sense.
* Controllers may or may not have alignment restrictions.
* As this is not exported, we use an extremely conservative guess.
*/ */
blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1)); blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment