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From:   Fenglin Wu <quic_fenglinw@quicinc.com>
To:     <linux-arm-msm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <sboyd@kernel.org>
CC:     <collinsd@codeaurora.org>, <subbaram@codeaurora.org>,
        <quic_fenglinw@quicinc.com>, <tglx@linutronix.de>, <maz@kernel.org>
Subject: [PATCH v5 07/10] spmi: pmic-arb: block access for invalid PMIC arbiter v5 SPMI writes
Date:   Wed, 26 Jan 2022 14:31:49 +0800
Message-ID: <1643178713-17178-8-git-send-email-quic_fenglinw@quicinc.com>
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References: <1643178713-17178-1-git-send-email-quic_fenglinw@quicinc.com>
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From: David Collins <collinsd@codeaurora.org>

The system crashes due to an access permission violation when
writing to a PMIC peripheral which is not owned by the current
ee.  Add a check for PMIC arbiter version 5 for such invalid
write requests and return an error instead of crashing the
system.

Signed-off-by: David Collins <collinsd@codeaurora.org>
Signed-off-by: Fenglin Wu <quic_fenglinw@quicinc.com>
---
 drivers/spmi/spmi-pmic-arb.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/spmi/spmi-pmic-arb.c b/drivers/spmi/spmi-pmic-arb.c
index cf92abc..39f25bc 100644
--- a/drivers/spmi/spmi-pmic-arb.c
+++ b/drivers/spmi/spmi-pmic-arb.c
@@ -1133,6 +1133,11 @@ static int pmic_arb_offset_v5(struct spmi_pmic_arb *pmic_arb, u8 sid, u16 addr,
 		offset = 0x10000 * pmic_arb->ee + 0x80 * apid;
 		break;
 	case PMIC_ARB_CHANNEL_RW:
+		if (pmic_arb->apid_data[apid].write_ee != pmic_arb->ee) {
+			dev_err(&pmic_arb->spmic->dev, "disallowed SPMI write to sid=%u, addr=0x%04X\n",
+				sid, addr);
+			return -EPERM;
+		}
 		offset = 0x10000 * apid;
 		break;
 	}
-- 
2.7.4