@@ -279,6 +279,9 @@ static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len)
struct usb_request *req = ffs->ep0req;
int ret;
+ if (!req)
+ return -EINVAL;
+
req->zero = len < le16_to_cpu(ffs->ev.setup.wLength);
spin_unlock_irq(&ffs->ev.waitq.lock);
@@ -1892,10 +1895,12 @@ static void functionfs_unbind(struct ffs_data *ffs)
ENTER();
if (!WARN_ON(!ffs->gadget)) {
+ mutex_lock(&ffs->mutex);
usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req);
ffs->ep0req = NULL;
ffs->gadget = NULL;
clear_bit(FFS_FL_BOUND, &ffs->flags);
+ mutex_unlock(&ffs->mutex);
ffs_data_put(ffs);
}
}
While performing fast composition switch, there is a possibility that the process of ffs_ep0_write/ffs_ep0_read get into a race condition due to ep0req being freed up from functionfs_unbind. Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't bounded so it can go ahead and mark the ep0req to NULL, and since there is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free. Fix this by making a serialized execution between the two functions using a mutex_lock(ffs->mutex). Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver") Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> --- drivers/usb/gadget/function/f_fs.c | 5 +++++ 1 file changed, 5 insertions(+)