From: Oliver Neukum <oneukum@suse.com> To: gregKH@linuxfoundation.org, linux-usb@vger.kernel.org Cc: Oliver Neukum <oneukum@suse.com> Subject: UAS: fix alignment of scatter/gather segments Date: Mon, 29 Apr 2019 14:20:26 +0200 [thread overview] Message-ID: <20190429122026.4249-1-oneukum@suse.com> (raw) This is the UAS version of 747668dbc061b3e62bc1982767a3a1f9815fcf0e 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. Signed-off-by: Oliver Neukum <oneukum@suse.com> --- drivers/usb/storage/uas.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 6d71b8fff9df..ec9c1c7bb156 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -789,24 +789,22 @@ static int uas_slave_alloc(struct scsi_device *sdev) { struct uas_dev_info *devinfo = (struct uas_dev_info *)sdev->host->hostdata; + int maxp; sdev->hostdata = devinfo; /* - * USB has unusual DMA-alignment requirements: Although the - * starting address of each scatter-gather element doesn't matter, - * the length of each element except the last must be divisible - * by the Bulk maxpacket value. There's currently no way to - * 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 - * values can be as large as 2048. To make that work properly - * will require changes to the block layer. + * USB has unusual scatter-gather requirements: the length of each + * scatterlist element except the last must be divisible by the + * Bulk maxpacket value. Fortunately this value is always a + * power of 2. Inform the block layer about this requirement. + */ + + maxp = usb_maxpacket(devinfo->udev, devinfo->data_in_pipe, 0); + blk_queue_virt_boundary(sdev->request_queue, maxp - 1); + + /* + * This one is for the controllers. We assume 512 is always good. */ blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1));
WARNING: multiple messages have this Message-ID (diff)
From: Oliver Neukum <oneukum@suse.com> To: gregKH@linuxfoundation.org, linux-usb@vger.kernel.org Cc: Oliver Neukum <oneukum@suse.com> Subject: [PATCH] UAS: fix alignment of scatter/gather segments Date: Mon, 29 Apr 2019 14:20:26 +0200 [thread overview] Message-ID: <20190429122026.4249-1-oneukum@suse.com> (raw) Message-ID: <20190429122026.6ms-KFpgxuWcobiJD0Iaooa16ni6T0N4nZI1oxA45DI@z> (raw) This is the UAS version of 747668dbc061b3e62bc1982767a3a1f9815fcf0e 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. Signed-off-by: Oliver Neukum <oneukum@suse.com> --- drivers/usb/storage/uas.c | 26 ++++++++++++-------------- 1 file changed, 12 insertions(+), 14 deletions(-) diff --git a/drivers/usb/storage/uas.c b/drivers/usb/storage/uas.c index 6d71b8fff9df..ec9c1c7bb156 100644 --- a/drivers/usb/storage/uas.c +++ b/drivers/usb/storage/uas.c @@ -789,24 +789,22 @@ static int uas_slave_alloc(struct scsi_device *sdev) { struct uas_dev_info *devinfo = (struct uas_dev_info *)sdev->host->hostdata; + int maxp; sdev->hostdata = devinfo; /* - * USB has unusual DMA-alignment requirements: Although the - * starting address of each scatter-gather element doesn't matter, - * the length of each element except the last must be divisible - * by the Bulk maxpacket value. There's currently no way to - * 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 - * values can be as large as 2048. To make that work properly - * will require changes to the block layer. + * USB has unusual scatter-gather requirements: the length of each + * scatterlist element except the last must be divisible by the + * Bulk maxpacket value. Fortunately this value is always a + * power of 2. Inform the block layer about this requirement. + */ + + maxp = usb_maxpacket(devinfo->udev, devinfo->data_in_pipe, 0); + blk_queue_virt_boundary(sdev->request_queue, maxp - 1); + + /* + * This one is for the controllers. We assume 512 is always good. */ blk_queue_update_dma_alignment(sdev->request_queue, (512 - 1)); -- 2.16.4
next reply other threads:[~2019-04-29 12:20 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-04-29 12:20 Oliver Neukum [this message] 2019-04-29 12:20 ` [PATCH] UAS: fix alignment of scatter/gather segments Oliver Neukum 2019-04-29 13:31 David Laight 2019-04-29 13:31 ` [PATCH] " David Laight 2019-04-29 13:38 Oliver Neukum 2019-04-29 13:38 ` [PATCH] " Oliver Neukum 2019-04-29 14:19 David Laight 2019-04-29 14:19 ` [PATCH] " David Laight 2019-04-29 14:32 Oliver Neukum 2019-04-29 14:32 ` [PATCH] " Oliver Neukum 2019-04-29 15:06 David Laight 2019-04-29 15:06 ` [PATCH] " David Laight 2019-04-29 15:57 Oliver Neukum 2019-04-29 15:57 ` [PATCH] " Oliver Neukum 2019-04-29 16:08 Alan Stern 2019-04-29 16:08 ` [PATCH] " Alan Stern 2019-04-29 16:58 Oliver Neukum 2019-04-29 16:58 ` [PATCH] " Oliver Neukum 2019-04-29 17:55 Alan Stern 2019-04-29 17:55 ` [PATCH] " Alan Stern 2019-04-29 18:42 Oliver Neukum 2019-04-29 18:42 ` [PATCH] " Oliver Neukum 2019-04-29 19:42 Alan Stern 2019-04-29 19:42 ` [PATCH] " Alan Stern 2019-04-30 9:16 David Laight 2019-04-30 9:16 ` [PATCH] " David Laight 2019-04-30 14:39 Alan Stern 2019-04-30 14:39 ` [PATCH] " Alan Stern
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