This is a note to let you know that I've just added the patch titled

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

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From a4b98a7512f18534ce33a7e98e49115af59ffa00 Mon Sep 17 00:00:00 2001

From: Vamsi Krishna Samavedam vskrishn@codeaurora.org Date: Mon, 30 Nov 2020 12:34:53 -0800 Subject: 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: c559a3534109 ("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 --- drivers/usb/gadget/function/f_fs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 046f770a76da..c727cb5de871 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -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;