From: Oliver Neukum <oneukum@suse.de>
Date: Wed, 26 Mar 2014 13:32:51 +0000 (+0100)
Subject: usbnet: include wait queue head in device structure
X-Git-Tag: v3.14~8^2~17
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=14a0d635d18d0fb552dcc979d6d25106e6541f2e;p=pandora-kernel.git

usbnet: include wait queue head in device structure

This fixes a race which happens by freeing an object on the stack.
Quoting Julius:
> The issue is
> that it calls usbnet_terminate_urbs() before that, which temporarily
> installs a waitqueue in dev->wait in order to be able to wait on the
> tasklet to run and finish up some queues. The waiting itself looks
> okay, but the access to 'dev->wait' is totally unprotected and can
> race arbitrarily. I think in this case usbnet_bh() managed to succeed
> it's dev->wait check just before usbnet_terminate_urbs() sets it back
> to NULL. The latter then finishes and the waitqueue_t structure on its
> stack gets overwritten by other functions halfway through the
> wake_up() call in usbnet_bh().

The fix is to just not allocate the data structure on the stack.
As dev->wait is abused as a flag it also takes a runtime PM change
to fix this bug.

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Reported-by: Grant Grundler <grundler@google.com>
Tested-by: Grant Grundler <grundler@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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