Re: [PATCH rdma-next v2] RDMA/mana_ib: hardening: Clamp adapter capability values from MANA_IB_GET_ADAPTER_CAP

[Leon Romanovsky <leon@kernel.org>]

On Thu, Mar 12, 2026 at 11:16:41AM -0700, Erni Sri Satya Vennela wrote:
> As part of MANA hardening for CVM, clamp hardware-reported adapter
> capability values from the MANA_IB_GET_ADAPTER_CAP response before
> they are used by the IB subsystem.
> 
> The response fields (max_qp_count, max_cq_count, max_mr_count,
> max_pd_count, max_inbound_read_limit, max_outbound_read_limit,
> max_qp_wr, max_send_sge_count, max_recv_sge_count) are u32 but are
> assigned to signed int members in struct ib_device_attr. If hardware
> returns a value exceeding INT_MAX, the implicit u32-to-int conversion
> produces a negative value, which can cause incorrect behavior in the
> IB core and userspace applications.

This sentence does not make sense in the context of the Linux kernel.  
The fundamental assumption is that the underlying hardware behaves  
correctly, and driver code should not attempt to guard against purely  
hypothetical failures. The kernel only implements such self‑protection  
when there is a documented hardware issue accompanied by official  
errata.

Thanks