> -----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: diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/ index 7750a9c..1df7da4 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; } -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
