bus: mhi: core: Validate channel ID when processing command completions

MHI reads the channel ID from the event ring element sent by the device which can be any value between 0 and 255. In order to prevent any out of bound accesses, add a check against the maximum number of channels supported by the controller and those channels not configured yet so as to skip processing of that event ring element.

Fixes 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device")

Signed-off-by Bhaumik Bhatt <[email protected]>

Reviewed-by Hemant Kumar <[email protected]>

Reviewed-by Manivannan Sadhasivam <[email protected]>

Reviewed-by Jeffrey Hugo <[email protected]>

Link https://lore.kernel.org/r/[email protected] open here

---
 drivers/bus/mhi/core/main.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

drivers/bus/mhi/core/main.c +12 -5

index 22acde1..fc9196f 100644
@@ -773,11 +773,18 @@ static void mhi_process_cmd_completion(struct mhi_controller *mhi_cntrl,
 	cmd_pkt = mhi_to_virtual(mhi_ring, ptr);
 
 	chan = MHI_TRE_GET_CMD_CHID(cmd_pkt);
-	mhi_chan = &mhi_cntrl->mhi_chan[chan];
-	write_lock_bh(&mhi_chan->lock);
-	mhi_chan->ccs = MHI_TRE_GET_EV_CODE(tre);
-	complete(&mhi_chan->completion);
-	write_unlock_bh(&mhi_chan->lock);
+
+	if (chan < mhi_cntrl->max_chan &&
+	    mhi_cntrl->mhi_chan[chan].configured) {
+		mhi_chan = &mhi_cntrl->mhi_chan[chan];
+		write_lock_bh(&mhi_chan->lock);
+		mhi_chan->ccs = MHI_TRE_GET_EV_CODE(tre);
+		complete(&mhi_chan->completion);
+		write_unlock_bh(&mhi_chan->lock);
+	} else {
+		dev_err(&mhi_cntrl->mhi_dev->dev,
+			"Completion packet for invalid channel ID: %d\n", chan);
+	}
 
 	mhi_del_ring_element(mhi_cntrl, mhi_ring);
 }

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