Re: [PATCH 7/7] usb: storage: shuttle_usbat: bound the READ chunk size

[sashiko-bot@kernel.org]

> From: Josef Bacik <josef@toxicpanda.com>
> 
> An SG_IO READ(10) of 64KiB or more to an HP 8200e CD-RW behind a USBAT
> bridge never makes progress: the usb-storage thread keeps issuing
> zero-length reads until the SCSI command times out and is aborted.
> 
> usbat_hp8200e_handle_read10() splits reads of 64KiB or more into chunks
> of whole sectors, using srb->transfersize as the sector size:
> 
>     len = (65535/srb->transfersize) * srb->transfersize;
> 
> For passthrough requests scsi_setup_scsi_cmnd() sets transfersize to
> the whole request size, and the READ CD path can likewise compute a
> value above 65535, so len becomes 0.  The loop then sends commands with
> a zero length and adds 0 to the transferred count on every pass.
> 
> The bug was found by code inspection and has not been reproduced.
> 
> Fix by falling back to the existing 2048-byte sector size guess when
> transfersize is larger than the maximum read size, so that every chunk
> holds at least one sector.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261027-llm-usb-storage-v1-0-d1655e94ed10@linuxfoundation.org?part=7