linux-kernel - [56/67] USB: serial: fix stalled writes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20100812000617.824920522@clark.site>
Date:	Wed, 11 Aug 2010 17:06:11 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Johan Hovold <jhovold@...il.com>
Subject: [56/67] USB: serial: fix stalled writes

2.6.35-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Johan Hovold <jhovold@...il.com>

commit b58af4066d240b18b43f202e07b9ec7461d90b17 upstream.

As David VomLehn points out, it was possible to receive an interrupt
before clearing the free-urb flag which could lead to the urb being
incorrectly marked as busy.

For the same reason, move tx_bytes accounting so that it will never be
negative.

Note that the free-flags set and clear operations do not need any
additional locking as they are manipulated while USB_SERIAL_WRITE_BUSY
is set.

Reported-by: David VomLehn <dvomlehn@...co.com>
Tested-by: David VomLehn <dvomlehn@...co.com>
Signed-off-by: Johan Hovold <jhovold@...il.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/usb/serial/generic.c |   15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -208,18 +208,23 @@ retry:
 	urb->transfer_buffer_length = count;
 	usb_serial_debug_data(debug, &port->dev, __func__, count,
 						urb->transfer_buffer);
+	spin_lock_irqsave(&port->lock, flags);
+	port->tx_bytes += count;
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	clear_bit(i, &port->write_urbs_free);
 	result = usb_submit_urb(urb, GFP_ATOMIC);
 	if (result) {
 		dev_err(&port->dev, "%s - error submitting urb: %d\n",
 						__func__, result);
+		set_bit(i, &port->write_urbs_free);
+		spin_lock_irqsave(&port->lock, flags);
+		port->tx_bytes -= count;
+		spin_unlock_irqrestore(&port->lock, flags);
+
 		clear_bit_unlock(USB_SERIAL_WRITE_BUSY, &port->flags);
 		return result;
 	}
-	clear_bit(i, &port->write_urbs_free);
-
-	spin_lock_irqsave(&port->lock, flags);
-	port->tx_bytes += count;
-	spin_unlock_irqrestore(&port->lock, flags);
 
 	/* Try sending off another urb, unless in irq context (in which case
 	 * there will be no free urb). */


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/