Re: [4.10, panic, regression] iscsi: null pointer deref at iscsi_tcp_segment_done+0x20d/0x2e0

[Hannes Reinecke]

On 12/24/2016 11:07 AM, Christoph Hellwig wrote:
> On Fri, Dec 23, 2016 at 11:42:45AM -0800, Linus Torvalds wrote:
> > Ugh. This patch is nasty.
>
> It's the same SCSI has done for ages - except that is uses a separate
> kmalloc for the sense buffer.
>
> > I think we should just fix blk_execute_rq() instead.
>
> As you found out below it's not just blk_execute_rq, it's the whole
> architecture of the BLOCK_PC code, which expects a caller provided
> sense buffer.  But with the way blk-mq allocates request structures
> we can actually fix it, but I first need to extent the way it allows
> drivers to allocate private data to the old request code.  I've
> actually already implemented that for SCSI long time ago, and have
> started to life it to the block layer.
Would be cool to have a generic sense buffer.
I always found it slightly odd, pretending that 'struct request' is 
protocol-agnostic and refusing to add a sense data pointer, but at the 
same time having a field 'sense_len' (which gives the length of what 
exactly?).

Christoph, do you have a pointer to your patchset?
Not that I'll be able to do any meaningful work until next year, but 
having a look would be nice. Just to get a feeling where you want to 
head to; I might be able to work on this start of January.

Cheers,

Hannes
--
Dr. Hannes Reinecke		      zSeries & Storage
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