[PATCH 6.6 222/396] usb: typec: altmodes/displayport: create sysfs nodes as drivers default device attribute group

Greg Kroah-Hartman
2024-04-01T16:46:57Z

From: RD Babiera <rdbabiera@google.com>

commit 165376f6b23e9a779850e750fb2eb06622e5a531 upstream.

The DisplayPort driver's sysfs nodes may be present to the userspace before
typec_altmode_set_drvdata() completes in dp_altmode_probe. This means that
a sysfs read can trigger a NULL pointer error by deferencing dp->hpd in
hpd_show or dp->lock in pin_assignment_show, as dev_get_drvdata() returns
NULL in those cases.

Remove manual sysfs node creation in favor of adding attribute group as
default for devices bound to the driver. The ATTRIBUTE_GROUPS() macro is
not used here otherwise the path to the sysfs nodes is no longer compliant
with the ABI.

Fixes: 0e3bb7d6894d ("usb: typec: Add driver for DisplayPort alternate mode")
Cc: stable@vger.kernel.org
Signed-off-by: RD Babiera <rdbabiera@google.com>
Link: https://lore.kernel.org/r/20240229001101.3889432-2-rdbabiera@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/typec/altmodes/displayport.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/usb/typec/altmodes/displayport.c
+++ b/drivers/usb/typec/altmodes/displayport.c
@@ -554,16 +554,21 @@ static ssize_t hpd_show(struct device *d
}
static DEVICE_ATTR_RO(hpd);

-static struct attribute *dp_altmode_attrs[] = {
+static struct attribute *displayport_attrs[] = {
&dev_attr_configuration.attr,
&dev_attr_pin_assignment.attr,
&dev_attr_hpd.attr,
NULL
};

-static const struct attribute_group dp_altmode_group = {
+static const struct attribute_group displayport_group = {
.name = "displayport",
- .attrs = dp_altmode_attrs,
+ .attrs = displayport_attrs,
+};
+
+static const struct attribute_group *displayport_groups[] = {
+ &displayport_group,
+ NULL,
};

int dp_altmode_probe(struct typec_altmode *alt)
@@ -571,7 +576,6 @@ int dp_altmode_probe(struct typec_altmod
const struct typec_altmode *port = typec_altmode_get_partner(alt);
struct fwnode_handle *fwnode;
struct dp_altmode *dp;
- int ret;

/* FIXME: Port can only be DFP_U. */

@@ -582,10 +586,6 @@ int dp_altmode_probe(struct typec_altmod
DP_CAP_PIN_ASSIGN_DFP_D(alt->vdo)))
return -ENODEV;

- ret = sysfs_create_group(&alt->dev.kobj, &dp_altmode_group);
- if (ret)
- return ret;
-
dp = devm_kzalloc(&alt->dev, sizeof(*dp), GFP_KERNEL);
if (!dp)
return -ENOMEM;
@@ -619,7 +619,6 @@ void dp_altmode_remove(struct typec_altm
{
struct dp_altmode *dp = typec_altmode_get_drvdata(alt);

- sysfs_remove_group(&alt->dev.kobj, &dp_altmode_group);
cancel_work_sync(&dp->work);

if (dp->connector_fwnode) {
@@ -644,6 +643,7 @@ static struct typec_altmode_driver dp_al
.driver = {
.name = "typec_displayport",
.owner = THIS_MODULE,
+ .dev_groups = displayport_groups,
},
};
module_typec_altmode_driver(dp_altmode_driver);