[PATCH 03/14] bus: mhi: core: Add range check for channel id received in event ring

mani
2020-05-21T15:26:12Z

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>
Reviewed-by: Jeffrey Hugo <jhugo@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
---
drivers/bus/mhi/core/main.c | 40 +++++++++++++++++++++++++++----------
1 file changed, 29 insertions(+), 11 deletions(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index beac8d33d1cb..64022865cb75 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -774,9 +774,18 @@ 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];
- parse_xfer_event(mhi_cntrl, local_rp, mhi_chan);
- event_quota--;
+
+ WARN_ON(chan >= mhi_cntrl->max_chan);
+
+ /*
+ * Only process the event ring elements whose channel
+ * ID is within the maximum supported range.
+ */
+ if (chan < mhi_cntrl->max_chan) {
+ mhi_chan = &mhi_cntrl->mhi_chan[chan];
+ parse_xfer_event(mhi_cntrl, local_rp, mhi_chan);
+ event_quota--;
+ }
break;
default:
dev_err(dev, "Unhandled event type: %d\n", type);
@@ -819,14 +828,23 @@ 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);
- mhi_chan = &mhi_cntrl->mhi_chan[chan];
-
- if (likely(type == MHI_PKT_TYPE_TX_EVENT)) {
- parse_xfer_event(mhi_cntrl, local_rp, mhi_chan);
- event_quota--;
- } else if (type == MHI_PKT_TYPE_RSC_TX_EVENT) {
- parse_rsc_event(mhi_cntrl, local_rp, mhi_chan);
- event_quota--;
+
+ WARN_ON(chan >= mhi_cntrl->max_chan);
+
+ /*
+ * Only process the event ring elements whose channel
+ * ID is within the maximum supported range.
+ */
+ if (chan < mhi_cntrl->max_chan) {
+ mhi_chan = &mhi_cntrl->mhi_chan[chan];
+
+ if (likely(type == MHI_PKT_TYPE_TX_EVENT)) {
+ parse_xfer_event(mhi_cntrl, local_rp, mhi_chan);
+ event_quota--;
+ } else if (type == MHI_PKT_TYPE_RSC_TX_EVENT) {
+ parse_rsc_event(mhi_cntrl, local_rp, mhi_chan);
+ event_quota--;
+ }
}

mhi_recycle_ev_ring_element(mhi_cntrl, ev_ring);
--
2.26.GIT