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From:   Krishna chaitanya chundru <quic_krichai@quicinc.com>
Date:   Mon, 23 Oct 2023 15:13:06 +0530
Subject: [PATCH] bus: mhi: host: Add alignment check for event ring read
 pointer
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Message-ID: <20231023-alignment_check-v1-1-2ca5716d5c15@quicinc.com>
To:     Manivannan Sadhasivam <mani@kernel.org>
CC:     <mhi@lists.linux.dev>, <linux-arm-msm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <quic_vbadigan@quicinc.com>,
        <quic_ramkri@quicinc.com>, <quic_skananth@quicinc.com>,
        <quic_parass@quicinc.com>,
        Krishna chaitanya chundru <quic_krichai@quicinc.com>
Precedence: bulk

Though we do check the event ring read pointer by "is_valid_ring_ptr"
to make sure it is in the buffer range, but there is another risk the
pointer may be not aligned.  Since we are expecting event ring elements
are 128 bits(struct mhi_tre) aligned, an unaligned read pointer could lead
to multiple issues like DoS or ring buffer memory corruption.

So add a alignment check for event ring read pointer.

Signed-off-by: Krishna chaitanya chundru <quic_krichai@quicinc.com>
---
 drivers/bus/mhi/host/main.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/mhi/host/main.c b/drivers/bus/mhi/host/main.c
index 499590437e9b..c907bbb67fb2 100644
--- a/drivers/bus/mhi/host/main.c
+++ b/drivers/bus/mhi/host/main.c
@@ -268,7 +268,7 @@ static void mhi_del_ring_element(struct mhi_controller *mhi_cntrl,
 
 static bool is_valid_ring_ptr(struct mhi_ring *ring, dma_addr_t addr)
 {
-	return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len;
+	return addr >= ring->iommu_base && addr < ring->iommu_base + ring->len && addr % 16 == 0;
 }
 
 int mhi_destroy_device(struct device *dev, void *data)

---
base-commit: 71e68e182e382e951d6248bccc3c960dcec5a718
change-id: 20231013-alignment_check-c013f509d24a

Best regards,
-- 
Krishna chaitanya chundru <quic_krichai@quicinc.com>