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] Link: https://lore.kernel.org/driver-core/[email protected]/ [1] Reported-by: Gui-Dong Han <[email protected]> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=220789 Fixes: 3cf385713460 ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'") Signed-off-by: Danilo Krummrich <[email protected]> --- drivers/amba/bus.c | 37 ++++++------------------------------- include/linux/amba/bus.h | 5 ----- 2 files changed, 6 insertions(+), 36 deletions(-) diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 6d479caf89cb..d721d64a9858 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -82,33 +82,6 @@ static void amba_put_disable_pclk(struct amba_device *pcdev) } -static ssize_t driver_override_show(struct device *_dev, - struct device_attribute *attr, char *buf) -{ - struct amba_device *dev = to_amba_device(_dev); - ssize_t len; - - device_lock(_dev); - len = sprintf(buf, "%s\n", dev->driver_override); - device_unlock(_dev); - return len; -} - -static ssize_t driver_override_store(struct device *_dev, - struct device_attribute *attr, - const char *buf, size_t count) -{ - struct amba_device *dev = to_amba_device(_dev); - int ret; - - ret = driver_set_override(_dev, &dev->driver_override, buf, count); - if (ret) - return ret; - - return count; -} -static DEVICE_ATTR_RW(driver_override); - #define amba_attr_func(name,fmt,arg...) \ static ssize_t name##_show(struct device *_dev, \ struct device_attribute *attr, char *buf) \ @@ -126,7 +99,6 @@ amba_attr_func(resource, "\t%016llx\t%016llx\t%016lx\n", static struct attribute *amba_dev_attrs[] = { &dev_attr_id.attr, &dev_attr_resource.attr, - &dev_attr_driver_override.attr, NULL, }; ATTRIBUTE_GROUPS(amba_dev); @@ -209,10 +181,11 @@ static int amba_match(struct device *dev, const struct device_driver *drv) { struct amba_device *pcdev = to_amba_device(dev); const struct amba_driver *pcdrv = to_amba_driver(drv); + int ret; mutex_lock(&pcdev->periphid_lock); if (!pcdev->periphid) { - int ret = amba_read_periphid(pcdev); + ret = amba_read_periphid(pcdev); /* * Returning any error other than -EPROBE_DEFER from bus match @@ -230,8 +203,9 @@ static int amba_match(struct device *dev, const struct device_driver *drv) mutex_unlock(&pcdev->periphid_lock); /* When driver_override is set, only bind to the matching driver */ - if (pcdev->driver_override) - return !strcmp(pcdev->driver_override, drv->name); + ret = device_match_driver_override(dev, drv); + if (ret >= 0) + return ret; return amba_lookup(pcdrv->id_table, pcdev) != NULL; } @@ -436,6 +410,7 @@ static const struct dev_pm_ops amba_pm = { const struct bus_type amba_bustype = { .name = "amba", .dev_groups = amba_dev_groups, + .driver_override = true, .match = amba_match, .uevent = amba_uevent, .probe = amba_probe, diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h index 9946276aff73..6c54d5c0d21f 100644 --- a/include/linux/amba/bus.h +++ b/include/linux/amba/bus.h @@ -71,11 +71,6 @@ struct amba_device { unsigned int cid; struct amba_cs_uci_id uci; unsigned int irq[AMBA_NR_IRQS]; - /* - * Driver name to force a match. Do not set directly, because core - * frees it. Use driver_set_override() to set or clear it. - */ - const char *driver_override; }; struct amba_driver { -- 2.53.0
