Commit a4b98a75 authored Nov 30, 2020 by Vamsi Krishna Samavedam Committed by Greg Kroah-Hartman Dec 04, 2020

usb: gadget: f_fs: Use local copy of descriptors for userspace copy



The function may be unbound causing the ffs_ep and its descriptors
to be freed while userspace is in the middle of an ioctl requesting
the same descriptors. Avoid dangling pointer reference by first
making a local copy of desctiptors before releasing the spinlock.

Fixes: c559a353 ("usb: gadget: f_fs: add ioctl returning ep descriptor")
Reviewed-by: Peter Chen <peter.chen@nxp.com>
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20201130203453.28154-1-jackp@codeaurora.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 45c57754

drivers/usb/gadget/function/f_fs.c

+4 −2

Original line number	Diff line number	Diff line
		@@ -1324,7 +1324,7 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
		case FUNCTIONFS_ENDPOINT_DESC:
		{
		int desc_idx;
		struct usb_endpoint_descriptor *desc;
		struct usb_endpoint_descriptor desc1, *desc;

		switch (epfile->ffs->gadget->speed) {
		case USB_SPEED_SUPER:
		@@ -1336,10 +1336,12 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
		default:
		desc_idx = 0;
		}

		desc = epfile->ep->descs[desc_idx];
		memcpy(&desc1, desc, desc->bLength);

		spin_unlock_irq(&epfile->ffs->eps_lock);
		ret = copy_to_user((void __user *)value, desc, desc->bLength);
		ret = copy_to_user((void __user *)value, &desc1, desc1.bLength);
		if (ret)
		ret = -EFAULT;
		return ret;

Admin message