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@xxxxxxxxxxxxxx>
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@xxxxxxx>
Signed-off-by: Vamsi Krishna Samavedam <vskrishn@xxxxxxxxxxxxxx>
Signed-off-by: Jack Pham <jackp@xxxxxxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20201130203453.28154-1-jackp@xxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
--
2.29.2
