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

[Hemant Kumar]

Hi Jeff

On 4/28/20 7:44 AM, Jeffrey Hugo wrote:
> On 4/27/2020 8:59 PM, Bhaumik Bhatt wrote:
> > From: Hemant Kumar <hemantk@xxxxxxxxxxxxxx>
> >
> > 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@xxxxxxxxxxxxxx>
> > Signed-off-by: Bhaumik Bhatt <bbhatt@xxxxxxxxxxxxxx>
> > ---
> > Â drivers/bus/mhi/core/main.c | 4 ++++
> > Â 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,
> > ÂÂÂÂÂÂÂÂÂ enum mhi_pkt_type type = MHI_TRE_GET_EV_TYPE(local_rp);
> > ÂÂÂÂÂÂÂÂÂ chan = MHI_TRE_GET_EV_CHID(local_rp);
> > +ÂÂÂÂÂÂÂ if (WARN_ON(chan >= mhi_cntrl->max_chan))
> > +ÂÂÂÂÂÂÂÂÂÂÂ goto next_event;
> > +
> > ÂÂÂÂÂÂÂÂÂ mhi_chan = &mhi_cntrl->mhi_chan[chan];
> > ÂÂÂÂÂÂÂÂÂ if (likely(type == MHI_PKT_TYPE_TX_EVENT)) {
> > @@ -837,6 +840,7 @@ int mhi_process_data_event_ring(struct 
> > mhi_controller *mhi_cntrl,
> > ÂÂÂÂÂÂÂÂÂÂÂÂÂ event_quota--;
> > ÂÂÂÂÂÂÂÂÂ }
> > +next_event:
> > ÂÂÂÂÂÂÂÂÂ mhi_recycle_ev_ring_element(mhi_cntrl, ev_ring);
> > ÂÂÂÂÂÂÂÂÂ local_rp = ev_ring->rp;
> > ÂÂÂÂÂÂÂÂÂ 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?
As discussed with you off line, spec allows to have just event ring to 
be used for both data and control. Updating this in V3.

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