[PATCH v3 3/9] bus: mhi: core: Add range check for channel id received in event ring

[Bhaumik Bhatt]

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>
---
 drivers/bus/mhi/core/main.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index aee64f9..b8e4aac 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -783,6 +783,9 @@ int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
 		case MHI_PKT_TYPE_TX_EVENT:
 			chan = MHI_TRE_GET_EV_CHID(local_rp);
 			mhi_chan = &mhi_cntrl->mhi_chan[chan];
+			if (WARN_ON(chan >= mhi_cntrl->max_chan))
+				goto next_event;
+
 			parse_xfer_event(mhi_cntrl, local_rp, mhi_chan);
 			event_quota--;
 			break;
@@ -791,6 +794,7 @@ int mhi_process_ctrl_ev_ring(struct mhi_controller *mhi_cntrl,
 			break;
 		}
 
+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);
@@ -827,6 +831,9 @@ 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 +844,7 @@ 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);
-- 
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