Re: [PATCH] RDMA/rxe: Fix configuration of atomic queue pair attributes

[Leon Romanovsky <leonro@mellanox.com>]

On Tue, Feb 18, 2020 at 05:53:56PM +0800, Zhu Yanjun wrote:
> Sorry, when max_rd_atomic will be set to 0?

User can set it.
ib_uverbs_ex_modify_qp()
 -> modify_qp()
  -> ib_modify_qp_with_udata()
   -> _ib_modify_qp()
    -> ib_security_modify_qp()
     -> .modify_q()
      -> rxe_modify_qp()
       -> rxe_qp_from_attr()

>
> Thanks,
> Zhu Yanjun
>
> On Tue, Feb 18, 2020 at 4:59 AM Bart Van Assche <bvanassche@acm.org> wrote:
> >
> > From the comment above the definition of the roundup_pow_of_two() macro:
> >
> >      The result is undefined when n == 0.
> >
> > Hence only pass positive values to roundup_pow_of_two(). This patch fixes
> > the following UBSAN complaint:
> >
> > UBSAN: Undefined behaviour in ./include/linux/log2.h:57:13
> > shift exponent 64 is too large for 64-bit type 'long unsigned int'
> > Call Trace:
> >  dump_stack+0xa5/0xe6
> >  ubsan_epilogue+0x9/0x26
> >  __ubsan_handle_shift_out_of_bounds.cold+0x4c/0xf9
> >  rxe_qp_from_attr.cold+0x37/0x5d [rdma_rxe]
> >  rxe_modify_qp+0x59/0x70 [rdma_rxe]
> >  _ib_modify_qp+0x5aa/0x7c0 [ib_core]
> >  ib_modify_qp+0x3b/0x50 [ib_core]
> >  cma_modify_qp_rtr+0x234/0x260 [rdma_cm]
> >  __rdma_accept+0x1a7/0x650 [rdma_cm]
> >  nvmet_rdma_cm_handler+0x1286/0x14cd [nvmet_rdma]
> >  cma_cm_event_handler+0x6b/0x330 [rdma_cm]
> >  cma_ib_req_handler+0xe60/0x22d0 [rdma_cm]
> >  cm_process_work+0x30/0x140 [ib_cm]
> >  cm_req_handler+0x11f4/0x1cd0 [ib_cm]
> >  cm_work_handler+0xb8/0x344e [ib_cm]
> >  process_one_work+0x569/0xb60
> >  worker_thread+0x7a/0x5d0
> >  kthread+0x1e6/0x210
> >  ret_from_fork+0x24/0x30
> >
> > Cc: Moni Shoua <monis@mellanox.com>
> > Fixes: 8700e3e7c485 ("Soft RoCE driver")
> > Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> > ---
> >  drivers/infiniband/sw/rxe/rxe_qp.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/infiniband/sw/rxe/rxe_qp.c b/drivers/infiniband/sw/rxe/rxe_qp.c
> > index ec21f616ac98..6c11c3aeeca6 100644
> > --- a/drivers/infiniband/sw/rxe/rxe_qp.c
> > +++ b/drivers/infiniband/sw/rxe/rxe_qp.c
> > @@ -590,15 +590,16 @@ int rxe_qp_from_attr(struct rxe_qp *qp, struct ib_qp_attr *attr, int mask,
> >         int err;
> >
> >         if (mask & IB_QP_MAX_QP_RD_ATOMIC) {
> > -               int max_rd_atomic = __roundup_pow_of_two(attr->max_rd_atomic);
> > +               int max_rd_atomic = attr->max_rd_atomic ?
> > +                       roundup_pow_of_two(attr->max_rd_atomic) : 0;
> >
> >                 qp->attr.max_rd_atomic = max_rd_atomic;
> >                 atomic_set(&qp->req.rd_atomic, max_rd_atomic);
> >         }
> >
> >         if (mask & IB_QP_MAX_DEST_RD_ATOMIC) {
> > -               int max_dest_rd_atomic =
> > -                       __roundup_pow_of_two(attr->max_dest_rd_atomic);
> > +               int max_dest_rd_atomic = attr->max_dest_rd_atomic ?
> > +                       roundup_pow_of_two(attr->max_dest_rd_atomic) : 0;
> >
> >                 qp->attr.max_dest_rd_atomic = max_dest_rd_atomic;
> >