linux-kernel - Re: [PATCH] USB: don't read past config->interface[] if usb_control_msg() fails in usb_reset

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Date:	Thu, 18 Feb 2010 02:36:23 +0100
From:	Roel Kluin <roel.kluin@...il.com>
To:	Greg KH <greg@...ah.com>
CC:	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Alan Stern <stern@...land.harvard.edu>,
	Greg Kroah-Hartman <gregkh@...e.de>, linux-usb@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] USB: don't read past config->interface[] if usb_control_msg()
 fails in usb_reset_configuration()

While looping over the interfaces, if usb_hcd_alloc_bandwidth() fails it calls
hcd->driver->reset_bandwidth(), so there was no need to reinstate the interface
again.

If no break occurred, the index equals config->desc.bNumInterfaces. A
subsequent usb_control_msg() failure resulted in a read from
config->interface[config->desc.bNumInterfaces] at label reset_old_alts.

In either case the last interface should be skipped.

Signed-off-by: Roel Kluin <roel.kluin@...il.com>
Acked-by: Alan Stern <stern@...land.harvard.edu>
Acked-by: Sarah Sharp <sarah.a.sharp@...ux.intel.com>
---
>> Could you please confirm whether this patch is the better or the
>> other (in this same thread)?
> 
> Can someone tell me which one is the correct one to apply, but resending
> it to me?

This is the one as Sarah kindly explained to me.

Thanks, Roel

diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index 9bc95fe..1a48aac 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -1471,7 +1471,7 @@ int usb_reset_configuration(struct usb_device *dev)
 	/* If not, reinstate the old alternate settings */
 	if (retval < 0) {
 reset_old_alts:
-		for (; i >= 0; i--) {
+		for (i--; i >= 0; i--) {
 			struct usb_interface *intf = config->interface[i];
 			struct usb_host_interface *alt;
 
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