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

commit a4b98a7512 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: c559a35341 ("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>
5.4-rM2-2.2.x-imx-squashed
Vamsi Krishna Samavedam 2020-11-30 12:34:53 -08:00 committed by Greg Kroah-Hartman
parent 4a77729b25
commit 8954745718
1 changed files with 4 additions and 2 deletions
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6
drivers/usb/gadget/function/f_fs.c
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@ -1328,7 +1328,7 @@ 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:
@ -1340,10 +1340,12 @@ 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;