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

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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>
This commit is contained in:
Vamsi Krishna Samavedam 2020-11-30 12:34:53 -08:00 committed by Greg Kroah-Hartman
parent 45c5775460
commit a4b98a7512
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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@ -1324,7 +1324,7 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
case FUNCTIONFS_ENDPOINT_DESC: case FUNCTIONFS_ENDPOINT_DESC:
{ {
int desc_idx; int desc_idx;
struct usb_endpoint_descriptor *desc; struct usb_endpoint_descriptor desc1, *desc;
switch (epfile->ffs->gadget->speed) { switch (epfile->ffs->gadget->speed) {
case USB_SPEED_SUPER: case USB_SPEED_SUPER:
@ -1336,10 +1336,12 @@ static long ffs_epfile_ioctl(struct file *file, unsigned code,
default: default:
desc_idx = 0; desc_idx = 0;
} }
desc = epfile->ep->descs[desc_idx]; desc = epfile->ep->descs[desc_idx];
memcpy(&desc1, desc, desc->bLength);
spin_unlock_irq(&epfile->ffs->eps_lock); 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) if (ret)
ret = -EFAULT; ret = -EFAULT;
return ret; return ret;