On Tue, Jan 09, 2018 at 02:16:59PM +0000, Ruhl, Michael J wrote: > > -----Original Message----- > > From: Dan Carpenter [mailto:dan.carpenter@xxxxxxxxxx] > > Sent: Tuesday, January 9, 2018 4:27 AM > > To: Marciniszyn, Mike <mike.marciniszyn@xxxxxxxxx>; Ruhl, Michael J > > <michael.j.ruhl@xxxxxxxxx> > > Cc: Dalessandro, Dennis <dennis.dalessandro@xxxxxxxxx>; Doug Ledford > > <dledford@xxxxxxxxxx>; Jason Gunthorpe <jgg@xxxxxxxx>; linux- > > rdma@xxxxxxxxxxxxxxx; kernel-janitors@xxxxxxxxxxxxxxx > > Subject: [PATCH] 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@xxxxxxxxxx> > > > > diff --git a/drivers/infiniband/hw/hfi1/file_ops.c > > b/drivers/infiniband/hw/hfi1/file_ops.c > > index 82086241aac3..3de1ac94bb85 100644 > > --- a/drivers/infiniband/hw/hfi1/file_ops.c > > +++ b/drivers/infiniband/hw/hfi1/file_ops.c > > @@ -763,10 +763,10 @@ static int complete_subctxt(struct hfi1_filedata *fd) > > } > > > > if (ret) { > > + __clear_bit(fd->subctxt, fd->uctxt->in_use_ctxts); > > 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); > > } > > > > Hi Dan, > > Thanks for catching this. > > However, the patch is not quite correct. > > The __clear_bit() spin_lock_irqsave/restore need stay together. The patch should be: > Oh. Yeah. I should have noticed that now the spin_lock is pointless. Let me resend. Thanks. regards, dan carpenter -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
