Re: [PATCH] bus: mhi: host: Range check CHDBOFF and ERDBOFF

[Manivannan Sadhasivam]

On Fri, Mar 17, 2023 at 09:14:19AM -0600, Jeffrey Hugo wrote:
> If the value read from the CHDBOFF and ERDBOFF registers is outside the
> range of the MHI register space then an invalid address might be computed
> which later causes a kernel panic.  Range check the read value to prevent
> a crash due to bad data from the device.
> 
> Fixes: 6cd330ae76ff ("bus: mhi: core: Add support for ringing channel/event ring doorbells")

Please CC stable list.

> Signed-off-by: Jeffrey Hugo <quic_jhugo@xxxxxxxxxxx>
> Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@xxxxxxxxxxx>
> ---
>  drivers/bus/mhi/host/init.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
> index 3d779ee..ae8ebcfb 100644
> --- a/drivers/bus/mhi/host/init.c
> +++ b/drivers/bus/mhi/host/init.c
> @@ -516,6 +516,12 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
>  		return -EIO;
>  	}
>  
> +	if (val >= mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB)) {
> +		dev_err(dev, "CHDB offset: 0x%x is out of range: 0x%zx\n",
> +			val, mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB));
> +		return -EINVAL;

Isn't -ERANGE a better errno here and also in other places of the driver?

Thanks,
Mani

> +	}
> +
>  	/* Setup wake db */
>  	mhi_cntrl->wake_db = base + val + (8 * MHI_DEV_WAKE_DB);
>  	mhi_cntrl->wake_set = false;
> @@ -532,6 +538,12 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
>  		return -EIO;
>  	}
>  
> +	if (val >= mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings)) {
> +		dev_err(dev, "ERDB offset: 0x%x is out of range: 0x%zx\n",
> +			val, mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings));
> +		return -EINVAL;
> +	}
> +
>  	/* Setup event db address for each ev_ring */
>  	mhi_event = mhi_cntrl->mhi_event;
>  	for (i = 0; i < mhi_cntrl->total_ev_rings; i++, val += 8, mhi_event++) {
> -- 
> 2.7.4
> 
> 

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