linux-kernel - [char-misc-next] mei: hdcp: bind only with i915 on the same PCH

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Date:   Thu, 12 Dec 2019 10:41:03 +0200
From:   Tomas Winkler <tomas.winkler@...el.com>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org,
        Tomas Winkler <tomas.winkler@...el.com>,
        stable@...r.kernel.org, Ramalingam C <ramalingam.c@...el.com>
Subject: [char-misc-next] mei: hdcp: bind only with i915 on the same PCH

The mei device and i915 must reside on the same
PCH in order for HDCP to work. Make the component
matching function enforce this requirement.

                   hdcp
                    |
   i915            mei
    |               |
    +----= PCH =----+

Cc: <stable@...r.kernel.org> v5.0+
Cc: Ramalingam C <ramalingam.c@...el.com>
Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
Reviewed-by: Alexander Usyskin <alexander.usyskin@...el.com>
---
 drivers/misc/mei/hdcp/mei_hdcp.c | 33 +++++++++++++++++++++++++++++---
 1 file changed, 30 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/mei/hdcp/mei_hdcp.c b/drivers/misc/mei/hdcp/mei_hdcp.c
index 93027fd96c71..4c596c646ac0 100644
--- a/drivers/misc/mei/hdcp/mei_hdcp.c
+++ b/drivers/misc/mei/hdcp/mei_hdcp.c
@@ -757,11 +757,38 @@ static const struct component_master_ops mei_component_master_ops = {
 	.unbind = mei_component_master_unbind,
 };
 
+/**
+ * mei_hdcp_component_match - compare function for matching mei hdcp.
+ *
+ *    The function checks if the driver is i915, the subcomponent is HDCP
+ *    and the grand parent of hdcp and the parent of i915 are the same
+ *    PCH device.
+ *
+ * @dev: master device
+ * @subcomponent: subcomponent to match (I915_COMPONENT_HDCP)
+ * @data: compare data (mei hdcp device)
+ *
+ * Return:
+ * * 1 - if components match
+ * * 0 - otherwise
+ */
 static int mei_hdcp_component_match(struct device *dev, int subcomponent,
 				    void *data)
 {
-	return !strcmp(dev->driver->name, "i915") &&
-	       subcomponent == I915_COMPONENT_HDCP;
+	struct device *base = data;
+
+	if (strcmp(dev->driver->name, "i915") ||
+	    subcomponent != I915_COMPONENT_HDCP)
+		return 0;
+
+	base = base->parent;
+	if (!base)
+		return 0;
+
+	base = base->parent;
+	dev = dev->parent;
+
+	return (base && dev && dev == base);
 }
 
 static int mei_hdcp_probe(struct mei_cl_device *cldev,
@@ -785,7 +812,7 @@ static int mei_hdcp_probe(struct mei_cl_device *cldev,
 
 	master_match = NULL;
 	component_match_add_typed(&cldev->dev, &master_match,
-				  mei_hdcp_component_match, comp_master);
+				  mei_hdcp_component_match, &cldev->dev);
 	if (IS_ERR_OR_NULL(master_match)) {
 		ret = -ENOMEM;
 		goto err_exit;
-- 
2.21.0