[PATCH v3] nvme: Fix handling of large MDTS values

[Christoph Hellwig]

On Fri, Apr 02, 2021 at 05:00:58AM +0000, Damien Le Moal wrote:
> On 2021/04/02 10:47, Bart Van Assche wrote:
> > Instead of triggering an integer overflow and undefined behavior if MDTS is
> > large, set max_hw_sectors to UINT_MAX.
> > 
> > Cc: Christoph Hellwig <hch at lst.de>
> > Cc: Sagi Grimberg <sagi at grimberg.me>
> > Cc: Keith Busch <kbusch at kernel.org>
> > Signed-off-by: Bart Van Assche <bvanassche at acm.org>
> > ---
> > 
> > Changes compared to v2: reduced the two max_hw_sectors = UINT_MAX statements into a single assignment.
> > Changes compared to v1: removed a dev_err() call.
> > 
> >  drivers/nvme/host/core.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
> > index 40215a0246e4..87d43309742b 100644
> > --- a/drivers/nvme/host/core.c
> > +++ b/drivers/nvme/host/core.c
> > @@ -3123,10 +3123,10 @@ static int nvme_init_identify(struct nvme_ctrl *ctrl)
> >  
> >  	atomic_set(&ctrl->abort_limit, id->acl + 1);
> >  	ctrl->vwc = id->vwc;
> > -	if (id->mdts)
> > -		max_hw_sectors = 1 << (id->mdts + page_shift - 9);
> > -	else
> > +	if (!id->mdts || check_shl_overflow(1U, id->mdts + page_shift - 9,
> > +					    &max_hw_sectors)) {
> >  		max_hw_sectors = UINT_MAX;
> > +	}
> 
> Nit: this could be rewritten as:
> 
> 	if (!id->mdts ||
> 	    check_shl_overflow(1U, id->mdts + page_shift - 9, &max_hw_sectors))
> 		max_hw_sectors = UINT_MAX;
> 
> More readable and no unneeded brackets. No ?

I'll just fix this up when applying the patch.