Re: [PATCH v2 2/8] bus: mhi: core: Add range check for channel id received in event ring

Jeffrey Hugo
2020-04-28T14:44:25Z

On 4/27/2020 8:59 PM, Bhaumik Bhatt wrote:
> From: Hemant Kumar <hemantk@codeaurora.org>
>
> MHI data completion handler function reads channel id from event
> ring element. Value is under the control of MHI devices and can be
> any value between 0 and 255. In order to prevent out of bound access
> add a bound check against the max channel supported by controller
> and skip processing of that event ring element.
>
> Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
> Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
> ---
> drivers/bus/mhi/core/main.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
> index 23154f1..1ccd4cc 100644
> --- a/drivers/bus/mhi/core/main.c
> +++ b/drivers/bus/mhi/core/main.c
> @@ -827,6 +827,9 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
> enum mhi_pkt_type type = MHI_TRE_GET_EV_TYPE(local_rp);
>
> chan = MHI_TRE_GET_EV_CHID(local_rp);
> + if (WARN_ON(chan >= mhi_cntrl->max_chan))
> + goto next_event;
> +
> mhi_chan = &mhi_cntrl->mhi_chan[chan];
>
> if (likely(type == MHI_PKT_TYPE_TX_EVENT)) {
> @@ -837,6 +840,7 @@ int mhi_process_data_event_ring(struct mhi_controller *mhi_cntrl,
> event_quota--;
> }
>
> +next_event:
> mhi_recycle_ev_ring_element(mhi_cntrl, ev_ring);
> local_rp = ev_ring->rp;
> dev_rp = mhi_to_virtual(ev_ring, er_ctxt->rp);
>

It looks like the same issue exists in mhi_process_ctrl_ev_ring(), and
thus some form of this solution needs to be applied there as well.
Would you please fix that too?

--
Jeffrey Hugo
Qualcomm Technologies, Inc. is a member of the
Code Aurora Forum, a Linux Foundation Collaborative Project.