Re: [PATCH v2] IB/hfi1: Prevent a NULL dereference

[Doug Ledford <dledford@redhat.com>]

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On Tue, 2018-01-09 at 20:39 +0000, Ruhl, Michael J wrote:
> > -----Original Message-----
> > From: linux-rdma-owner@vger.kernel.org [mailto:linux-rdma-
> > owner@vger.kernel.org] On Behalf Of Dan Carpenter
> > Sent: Tuesday, January 9, 2018 3:04 PM
> > To: Marciniszyn, Mike <mike.marciniszyn@intel.com>
> > Cc: Dalessandro, Dennis <dennis.dalessandro@intel.com>; Doug Ledford
> > <dledford@redhat.com>; Jason Gunthorpe <jgg@ziepe.ca>; linux-
> > rdma@vger.kernel.org; kernel-janitors@vger.kernel.org
> > Subject: [PATCH v2] IB/hfi1: Prevent a NULL dereference
> > 
> > In the original code, we set "fd->uctxt" to NULL and then dereference it
> > which will cause an Oops.
> > 
> > Fixes: f2a3bc00a03c ("IB/hfi1: Protect context array set/clear with spinlock")
> > Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> > ---
> > v2: In v1, I accidentally moved the __clear_bit() out from under the
> >     spin_lock().  Thanks for the review, Michael!
> > 
> > diff --git a/drivers/infiniband/hw/hfi1/file_ops.c
> > b/drivers/infiniband/hw/hfi1/file_ops.c
> > index 82086241aac3..bd6f03cc5ee0 100644
> > --- a/drivers/infiniband/hw/hfi1/file_ops.c
> > +++ b/drivers/infiniband/hw/hfi1/file_ops.c
> > @@ -763,11 +763,11 @@ static int complete_subctxt(struct hfi1_filedata *fd)
> >  	}
> > 
> >  	if (ret) {
> > -		hfi1_rcd_put(fd->uctxt);
> > -		fd->uctxt = NULL;
> >  		spin_lock_irqsave(&fd->dd->uctxt_lock, flags);
> >  		__clear_bit(fd->subctxt, fd->uctxt->in_use_ctxts);
> >  		spin_unlock_irqrestore(&fd->dd->uctxt_lock, flags);
> > +		hfi1_rcd_put(fd->uctxt);
> > +		fd->uctxt = NULL;
> >  	}
> > 
> >  	return ret;
> > --
> 
> Cc: <stable@vger.kernel.org> # 4.14.x

Unfortunately, patchworks doesn't pick up additional Cc: tags, only
reviewed-bys and acks.  In any case, I hand added it.  Thanks, applied
to for-rc.

> Reviewed-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
> 
> Looks good.  Adding tag for stable too.
> 
> Thanks,
> 
> Mike
> 
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-- 
Doug Ledford <dledford@redhat.com>
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