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bus: fsl-mc: use generic driver_override infrastructure

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When a driver is probed through __driver_attach(), the bus' match()
callback is called without the device lock held, thus accessing the
driver_override field without a lock, which can cause a UAF.

Fix this by using the driver-core driver_override infrastructure taking
care of proper locking internally.

Note that calling match() from __driver_attach() without the device lock
held is intentional. [1]

Tested-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Acked-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Acked-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Link: https://lore.kernel.org/driver-core/DGRGTIRHA62X.3RY09D9SOK77P@kernel.org/ [1]
Reported-by: Gui-Dong Han <hanguidong02@gmail.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789
Fixes: 1f86a00c11 ("bus/fsl-mc: add support for 'driver_override' in the mc-bus")
Link: https://patch.msgid.link/20260324005919.2408620-3-dakr@kernel.org
Signed-off-by: Danilo Krummrich <dakr@kernel.org>
This commit is contained in:
Danilo Krummrich
2026-03-24 01:59:06 +01:00
parent 81d6f7c3a7
commit 6c8dfb0362
3 changed files with 8 additions and 43 deletions
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43
drivers/bus/fsl-mc/fsl-mc-bus.c
View File

@@ -86,12 +86,16 @@ static int fsl_mc_bus_match(struct device *dev, const struct device_driver *drv)
struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
const struct fsl_mc_driver *mc_drv = to_fsl_mc_driver(drv);
bool found = false;
int ret;
/* When driver_override is set, only bind to the matching driver */
if (mc_dev->driver_override) {
found = !strcmp(mc_dev->driver_override, mc_drv->driver.name);
ret = device_match_driver_override(dev, drv);
if (ret > 0) {
found = true;
goto out;
}
if (ret == 0)
goto out;
if (!mc_drv->match_id_table)
goto out;
@@ -210,39 +214,8 @@ static ssize_t modalias_show(struct device *dev, struct device_attribute *attr,
}
static DEVICE_ATTR_RO(modalias);
static ssize_t driver_override_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t count)
{
struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
int ret;
if (WARN_ON(dev->bus != &fsl_mc_bus_type))
return -EINVAL;
ret = driver_set_override(dev, &mc_dev->driver_override, buf, count);
if (ret)
return ret;
return count;
}
static ssize_t driver_override_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct fsl_mc_device *mc_dev = to_fsl_mc_device(dev);
ssize_t len;
device_lock(dev);
len = sysfs_emit(buf, "%s\n", mc_dev->driver_override);
device_unlock(dev);
return len;
}
static DEVICE_ATTR_RW(driver_override);
static struct attribute *fsl_mc_dev_attrs[] = {
&dev_attr_modalias.attr,
&dev_attr_driver_override.attr,
NULL,
};
@@ -345,6 +318,7 @@ ATTRIBUTE_GROUPS(fsl_mc_bus);
const struct bus_type fsl_mc_bus_type = {
.name = "fsl-mc",
.driver_override = true,
.match = fsl_mc_bus_match,
.uevent = fsl_mc_bus_uevent,
.probe = fsl_mc_probe,
@@ -910,9 +884,6 @@ static struct notifier_block fsl_mc_nb;
*/
void fsl_mc_device_remove(struct fsl_mc_device *mc_dev)
{
kfree(mc_dev->driver_override);
mc_dev->driver_override = NULL;
/*
* The device-specific remove callback will get invoked by device_del()
*/

4
drivers/vfio/fsl-mc/vfio_fsl_mc.c
View File

@@ -424,9 +424,7 @@ static int vfio_fsl_mc_bus_notifier(struct notifier_block *nb,
if (action == BUS_NOTIFY_ADD_DEVICE &&
vdev->mc_dev == mc_cont) {
mc_dev->driver_override = kasprintf(GFP_KERNEL, "%s",
vfio_fsl_mc_ops.name);
if (!mc_dev->driver_override)
if (device_set_driver_override(dev, vfio_fsl_mc_ops.name))
dev_warn(dev, "VFIO_FSL_MC: Setting driver override for device in dprc %s failed\n",
dev_name(&mc_cont->dev));
else

4
include/linux/fsl/mc.h
View File

@@ -178,9 +178,6 @@ struct fsl_mc_obj_desc {
* @regions: pointer to array of MMIO region entries
* @irqs: pointer to array of pointers to interrupts allocated to this device
* @resource: generic resource associated with this MC object device, if any.
* @driver_override: driver name to force a match; do not set directly,
* because core frees it; use driver_set_override() to
* set or clear it.
*
* Generic device object for MC object devices that are "attached" to a
* MC bus.
@@ -214,7 +211,6 @@ struct fsl_mc_device {
struct fsl_mc_device_irq **irqs;
struct fsl_mc_resource *resource;
struct device_link *consumer_link;
const char *driver_override;
};
#define to_fsl_mc_device(_dev) \