linux-kernel - [PATCH 2/3] bus: mhi: core: Validate channel ID when processing command completions

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Message-Id: <20210716075106.49938-3-manivannan.sadhasivam@linaro.org>
Date:   Fri, 16 Jul 2021 13:21:05 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     gregkh@...uxfoundation.org
Cc:     hemantk@...eaurora.org, bbhatt@...eaurora.org,
        linux-arm-msm@...r.kernel.org, jhugo@...eaurora.org,
        linux-kernel@...r.kernel.org, loic.poulain@...aro.org,
        stable@...r.kernel.org,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Jeffrey Hugo <quic_jhugo@...cinc.com>
Subject: [PATCH 2/3] bus: mhi: core: Validate channel ID when processing command completions

From: Bhaumik Bhatt <bbhatt@...eaurora.org>

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.

Cc: stable@...r.kernel.org #5.10
Fixes: 1d3173a3bae7 ("bus: mhi: core: Add support for processing events from client device")
Signed-off-by: Bhaumik Bhatt <bbhatt@...eaurora.org>
Reviewed-by: Hemant Kumar <hemantk@...eaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
Reviewed-by: Jeffrey Hugo <quic_jhugo@...cinc.com>
Link: https://lore.kernel.org/r/1624558141-11045-1-git-send-email-bbhatt@codeaurora.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
---
 drivers/bus/mhi/core/main.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 22acde118bc3..fc9196f11cb7 100644
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -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);
 }
-- 
2.25.1