From: John Keeping john@metanate.com
[ Upstream commit 89ff3dfac604614287ad5aad9370c3f984ea3f4b ]
The embedded struct cdev does not have its lifetime correctly tied to the enclosing struct f_hidg, so there is a use-after-free if /dev/hidgN is held open while the gadget is deleted.
This can readily be replicated with libusbgx's example programs (for conciseness - operating directly via configfs is equivalent):
gadget-hid exec 3<> /dev/hidg0 gadget-vid-pid-remove exec 3<&-
Pull the existing device up in to struct f_hidg and make use of the cdev_device_{add,del}() helpers. This changes the lifetime of the device object to match struct f_hidg, but note that it is still added and deleted at the same time.
Fixes: 71adf1189469 ("USB: gadget: add HID gadget driver") Tested-by: Lee Jones lee@kernel.org Reviewed-by: Andrzej Pietrasiewicz andrzej.p@collabora.com Reviewed-by: Lee Jones lee@kernel.org Signed-off-by: John Keeping john@metanate.com Link: https://lore.kernel.org/r/20221122123523.3068034-2-john@metanate.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/usb/gadget/function/f_hid.c | 52 ++++++++++++++++------------- 1 file changed, 28 insertions(+), 24 deletions(-)
diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c index 0c200f152036..2aaa3ea74e5a 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -71,7 +71,7 @@ struct f_hidg { wait_queue_head_t write_queue; struct usb_request *req;
- int minor; + struct device dev; struct cdev cdev; struct usb_function func;
@@ -84,6 +84,14 @@ static inline struct f_hidg *func_to_hidg(struct usb_function *f) return container_of(f, struct f_hidg, func); }
+static void hidg_release(struct device *dev) +{ + struct f_hidg *hidg = container_of(dev, struct f_hidg, dev); + + kfree(hidg->set_report_buf); + kfree(hidg); +} + /*-------------------------------------------------------------------------*/ /* Static descriptors */
@@ -910,9 +918,7 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f) struct usb_ep *ep; struct f_hidg *hidg = func_to_hidg(f); struct usb_string *us; - struct device *device; int status; - dev_t dev;
/* maybe allocate device-global string IDs, and patch descriptors */ us = usb_gstrings_attach(c->cdev, ct_func_strings, @@ -1005,21 +1011,11 @@ static int hidg_bind(struct usb_configuration *c, struct usb_function *f)
/* create char device */ cdev_init(&hidg->cdev, &f_hidg_fops); - dev = MKDEV(major, hidg->minor); - status = cdev_add(&hidg->cdev, dev, 1); + status = cdev_device_add(&hidg->cdev, &hidg->dev); if (status) goto fail_free_descs;
- device = device_create(hidg_class, NULL, dev, NULL, - "%s%d", "hidg", hidg->minor); - if (IS_ERR(device)) { - status = PTR_ERR(device); - goto del; - } - return 0; -del: - cdev_del(&hidg->cdev); fail_free_descs: usb_free_all_descriptors(f); fail: @@ -1250,9 +1246,7 @@ static void hidg_free(struct usb_function *f)
hidg = func_to_hidg(f); opts = container_of(f->fi, struct f_hid_opts, func_inst); - kfree(hidg->report_desc); - kfree(hidg->set_report_buf); - kfree(hidg); + put_device(&hidg->dev); mutex_lock(&opts->lock); --opts->refcnt; mutex_unlock(&opts->lock); @@ -1262,8 +1256,7 @@ static void hidg_unbind(struct usb_configuration *c, struct usb_function *f) { struct f_hidg *hidg = func_to_hidg(f);
- device_destroy(hidg_class, MKDEV(major, hidg->minor)); - cdev_del(&hidg->cdev); + cdev_device_del(&hidg->cdev, &hidg->dev);
usb_free_all_descriptors(f); } @@ -1272,6 +1265,7 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi) { struct f_hidg *hidg; struct f_hid_opts *opts; + int ret;
/* allocate and initialize one new instance */ hidg = kzalloc(sizeof(*hidg), GFP_KERNEL); @@ -1283,17 +1277,27 @@ static struct usb_function *hidg_alloc(struct usb_function_instance *fi) mutex_lock(&opts->lock); ++opts->refcnt;
- hidg->minor = opts->minor; + device_initialize(&hidg->dev); + hidg->dev.release = hidg_release; + hidg->dev.class = hidg_class; + hidg->dev.devt = MKDEV(major, opts->minor); + ret = dev_set_name(&hidg->dev, "hidg%d", opts->minor); + if (ret) { + --opts->refcnt; + mutex_unlock(&opts->lock); + return ERR_PTR(ret); + } + hidg->bInterfaceSubClass = opts->subclass; hidg->bInterfaceProtocol = opts->protocol; hidg->report_length = opts->report_length; hidg->report_desc_length = opts->report_desc_length; if (opts->report_desc) { - hidg->report_desc = kmemdup(opts->report_desc, - opts->report_desc_length, - GFP_KERNEL); + hidg->report_desc = devm_kmemdup(&hidg->dev, opts->report_desc, + opts->report_desc_length, + GFP_KERNEL); if (!hidg->report_desc) { - kfree(hidg); + put_device(&hidg->dev); mutex_unlock(&opts->lock); return ERR_PTR(-ENOMEM); }