Re: [PATCH v3 1/2] RDMA/rxe: Reject IB_ACCESS_ON_DEMAND changes after MR creation

[sashiko-bot@kernel.org]

> From: Norbert Szetei <norbert@doyensec.com>
> 
> Whether an MR is an ODP MR is decided once, at registration time:
> rxe_reg_user_mr() picks rxe_odp_mr_init_user() over rxe_mr_init_user()
> based on IB_ACCESS_ON_DEMAND, and only the former builds an ib_umem_odp
> via ib_umem_odp_get(). The umem cannot change type afterwards, and
> is_odp_mr() reads mr->umem->is_odp.
> 
> Two paths assign mr->access after that point and can leave it
> describing an MR type the umem does not have:
> 
> rxe_rereg_user_mr() with IB_MR_REREG_ACCESS overwrites mr->access with
> the caller's value, and IB_ACCESS_ON_DEMAND is part of
> RXE_ACCESS_SUPPORTED_MR, so userspace can set the flag on a plain MR or
> clear it on an ODP MR while the umem stays what it was.
> 
> rxe_reg_fast_mr() takes mr->access from the REG_MR work request
> unmasked and moves the MR to RXE_MR_STATE_VALID, on an MR that
> rxe_mr_init_fast() left with a NULL umem.
> 
> Reject IB_ACCESS_ON_DEMAND in both, so mr->access carries the flag only
> for an MR that has an ODP umem and the flag can be used to identify one.
> 
> Fixes: 544c7f62cf32 ("RDMA/rxe: Implement rereg_user_mr")
> Cc: stable@vger.kernel.org
> Signed-off-by: Norbert Szetei <norbert@doyensec.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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