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From:   Cristian Marussi <cristian.marussi@arm.com>
To:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc:     sudeep.holla@arm.com, cristian.marussi@arm.com
Subject: [PATCH 4/6] firmware: arm_scmi: Harden accesses to Reset domains
Date:   Wed, 17 Aug 2022 18:27:29 +0100
Message-Id: <20220817172731.1185305-5-cristian.marussi@arm.com>
In-Reply-To: <20220817172731.1185305-1-cristian.marussi@arm.com>
References: <20220817172731.1185305-1-cristian.marussi@arm.com>
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Accessing Reset domains descriptors by index upon SCMI drivers requests
through the SCMI reset operations interface can potentially lead to
out-of-bound violations if the SCMI driver misbehave.

Add an internal consistency check in front of such domains descriptors
accesses.

Fixes: 95a15d80aa0de ("firmware: arm_scmi: Add RESET protocol in SCMI v2.0")
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
---
 drivers/firmware/arm_scmi/reset.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/reset.c b/drivers/firmware/arm_scmi/reset.c
index 673f3eb498f4..b0494165b1cb 100644
--- a/drivers/firmware/arm_scmi/reset.c
+++ b/drivers/firmware/arm_scmi/reset.c
@@ -166,8 +166,12 @@ static int scmi_domain_reset(const struct scmi_protocol_handle *ph, u32 domain,
 	struct scmi_xfer *t;
 	struct scmi_msg_reset_domain_reset *dom;
 	struct scmi_reset_info *pi = ph->get_priv(ph);
-	struct reset_dom_info *rdom = pi->dom_info + domain;
+	struct reset_dom_info *rdom;
 
+	if (domain >= pi->num_domains)
+		return -EINVAL;
+
+	rdom = pi->dom_info + domain;
 	if (rdom->async_reset)
 		flags |= ASYNCHRONOUS_RESET;
 
-- 
2.32.0