This is a note to let you know that I've just added the patch titled
USB: gadgetfs: fix copy_to_user while holding spinlock
to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-gadgetfs-fix-copy_to_user-while-holding-spinlock.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6e76c01e71551cb221c1f3deacb9dcd9a7346784 Mon Sep 17 00:00:00 2001
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Date: Thu, 21 Sep 2017 16:12:01 -0400
Subject: USB: gadgetfs: fix copy_to_user while holding spinlock
From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
commit 6e76c01e71551cb221c1f3deacb9dcd9a7346784 upstream.
The gadgetfs driver as a long-outstanding FIXME, regarding a call of
copy_to_user() made while holding a spinlock. This patch fixes the
issue by dropping the spinlock and using the dev->udc_usage mechanism
introduced by another recent patch to guard against status changes
while the lock isn't held.
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-by: Andrey Konovalov <andreyknvl@xxxxxxxxxx>
Acked-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/usb/gadget/legacy/inode.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/usb/gadget/legacy/inode.c
+++ b/drivers/usb/gadget/legacy/inode.c
@@ -985,11 +985,14 @@ ep0_read (struct file *fd, char __user *
retval = -EIO;
else {
len = min (len, (size_t)dev->req->actual);
-// FIXME don't call this with the spinlock held ...
+ ++dev->udc_usage;
+ spin_unlock_irq(&dev->lock);
if (copy_to_user (buf, dev->req->buf, len))
retval = -EFAULT;
else
retval = len;
+ spin_lock_irq(&dev->lock);
+ --dev->udc_usage;
clean_req (dev->gadget->ep0, dev->req);
/* NOTE userspace can't yet choose to stall */
}
Patches currently in stable-queue which might be from stern@xxxxxxxxxxxxxxxxxxx are
queue-4.4/usb-dummy-hcd-fix-infinite-loop-resubmission-bug.patch
queue-4.4/usb-storage-unusual_devs-entry-to-fix-write-access-regression-for-seagate-external-drives.patch
queue-4.4/usb-gadgetfs-fix-copy_to_user-while-holding-spinlock.patch
queue-4.4/usb-devio-don-t-corrupt-user-memory.patch
queue-4.4/usb-gadgetfs-fix-crash-caused-by-inadequate-synchronization.patch
queue-4.4/usb-dummy-hcd-fix-connection-failures-wrong-speed.patch
queue-4.4/usb-dummy-hcd-fix-erroneous-synchronization-change.patch