[PATCH 5.4 10/16] firmware: arm_scmi: Harden accesses to the reset domains

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

5.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Cristian Marussi <cristian.marussi@arm.com>

commit e9076ffbcaed5da6c182b144ef9f6e24554af268 upstream.

Accessing reset domains descriptors by the index upon the 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 before any such domains descriptors
accesses.

Link: https://lore.kernel.org/r/20220817172731.1185305-5-cristian.marussi@arm.com
Signed-off-by: Cristian Marussi <cristian.marussi@arm.com>
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Signed-off-by: Dominique Martinet <dominique.martinet@atmark-techno.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/firmware/arm_scmi/reset.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/firmware/arm_scmi/reset.c
+++ b/drivers/firmware/arm_scmi/reset.c
@@ -135,8 +135,12 @@ static int scmi_domain_reset(const struc
 	struct scmi_xfer *t;
 	struct scmi_msg_reset_domain_reset *dom;
 	struct scmi_reset_info *pi = handle->reset_priv;
-	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;