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Commit 974c9391 authored by Vamsi Krishna Samavedam's avatar Vamsi Krishna Samavedam Committed by Greg Kroah-Hartman
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usb: gadget: f_fs: Use local copy of descriptors for userspace copy 



commit a4b98a7512f18534ce33a7e98e49115af59ffa00 upstream.

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: default avatarPeter Chen <peter.chen@nxp.com>
Signed-off-by: default avatarVamsi Krishna Samavedam <vskrishn@codeaurora.org>
Signed-off-by: default avatarJack 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent cbb8de54

drivers/usb/gadget/function/f_fs.c

+4 −2
Original line number Diff line number Diff line
@@ -1243,7 +1243,7 @@ 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:
@@ -1255,10 +1255,12 @@ 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;