Re: [PATCH] scsi: megaraid_sas: fix PRP list out-of-bounds write

Hi all,

Sorry for the late reply. I was unable to follow up on this earlier because I had to prioritize other issues.

In the meantime, we pinned our kernel to version 6.8.12-4-pve on Proxmox, which has been stable for our use case and hardware. Given the recent 7.x release, I will take another look this week and report back.

We are using KIOXIA NVMe SSDs, so we will see how it goes.

Thanks,
Daniel




On Sunday, July 12th, 2026 at 8:16 PM, Martin K. Petersen <[email protected]> wrote:

>
> Thorsten,
>
> > Martin, do you know if someone there ever looked into this regression
> > and the proposed fix? I'm wondering because Daniel and Mats reported
> > problems under the same subject line (in new threads), but also didn't
> > get a reply.
>
> I think this problem is just an unfortunate side effect of the kernel
> being able to build bigger I/Os by default.
>
> Typically NVMe SSDs report fairly modest maximum I/O sizes compared to
> SCSI devices. I suspect this is why we only see this issue with a few
> select models. My hunch is that these drives advertise a fairly large
> MDTS.
>
> Since there appears to be no traction wrt. fixing the MR PRP vs. SGL
> chaining logic, I wonder if the patch below is sufficient?
>
> --
> Martin K. Petersen
>
> diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
> index ecd365d78ae3..b93a6d1180ff 100644
> --- a/drivers/scsi/megaraid/megaraid_sas_base.c
> +++ b/drivers/scsi/megaraid/megaraid_sas_base.c
> @@ -1978,7 +1978,8 @@ megasas_set_nvme_device_properties(struct scsi_device *sdev,
>  	mr_nvme_pg_size = max_t(u32, instance->nvme_page_size,
>  				MR_DEFAULT_NVME_PAGE_SIZE);
>
> -	lim->max_hw_sectors = max_io_size / 512;
> +	lim->max_hw_sectors =
> +		min(SZ_2M >> SECTOR_SHIFT, max_io_size >> SECTOR_SHIFT);
>  	lim->virt_boundary_mask = mr_nvme_pg_size - 1;
>  }
>
>