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

Bhaumik Bhatt
2020-04-28T02:59:44Z

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);