Re: Oops in scsi_send_eh_cmnd 2.6.21-rc5-git6,7,10,13

James Bottomley
2007-04-06T00:52:04Z

On Thu, 2007-04-05 at 17:15 -0700, David Miller wrote:
> This won't work I believe.
>
> There are cases that use smaller sense buffers than the minimum
> specified by the SCSI layer.
>
> One example is that do_sr_ioctl() stuff when the cgc passed
> in has a sense buffer. That will only be as large as a
> "struct request_sense".
>
> I'm pretty sure that's one of the reasons why we cons up a local sense
> buffer in this EH code.
>
> So we could walk past the end of that and corrupt memory with
> your patch.

That should be fine ... the application copies the sense out of
scmnd->sense_buffer ... it can take as much or as little as it wants
(sense_buffer is actually a SCSI_SENSE_BUFFERSIZE array inside the
command). There was one thing I missed, which is that the sense buffer
size of the command is 252, whereas I need to set it back down to
sizeof(scmnd->sense_buffer).

This is another area where we "could do better" ... the request actually
gives us a sense buffer, but we use our own and later copy data out of
it back into the request.

James