[PATCH v2] bus: mhi: host: Range check CHDBOFF and ERDBOFF

[Jeffrey Hugo <quic_jhugo@quicinc.com>]

If the value read from the CHDBOFF and ERDBOFF registers is outside the
range of the MHI register space then an invalid address might be computed
which later causes a kernel panic.  Range check the read value to prevent
a crash due to bad data from the device.

Fixes: 6cd330ae76ff ("bus: mhi: core: Add support for ringing channel/event ring doorbells")
Cc: stable@vger.kernel.org
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
---

v2:
-CC stable
-Use ERANGE for the error code

 drivers/bus/mhi/host/init.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
index 3d779ee..b46a082 100644
--- a/drivers/bus/mhi/host/init.c
+++ b/drivers/bus/mhi/host/init.c
@@ -516,6 +516,12 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
 		return -EIO;
 	}
 
+	if (val >= mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB)) {
+		dev_err(dev, "CHDB offset: 0x%x is out of range: 0x%zx\n",
+			val, mhi_cntrl->reg_len - (8 * MHI_DEV_WAKE_DB));
+		return -ERANGE;
+	}
+
 	/* Setup wake db */
 	mhi_cntrl->wake_db = base + val + (8 * MHI_DEV_WAKE_DB);
 	mhi_cntrl->wake_set = false;
@@ -532,6 +538,12 @@ int mhi_init_mmio(struct mhi_controller *mhi_cntrl)
 		return -EIO;
 	}
 
+	if (val >= mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings)) {
+		dev_err(dev, "ERDB offset: 0x%x is out of range: 0x%zx\n",
+			val, mhi_cntrl->reg_len - (8 * mhi_cntrl->total_ev_rings));
+		return -ERANGE;
+	}
+
 	/* Setup event db address for each ev_ring */
 	mhi_event = mhi_cntrl->mhi_event;
 	for (i = 0; i < mhi_cntrl->total_ev_rings; i++, val += 8, mhi_event++) {
-- 
2.7.4