linux-kernel - [PATCH] usb-gadget-ether: Prevent oops caused by error interrupt race -V2 (comments update)

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]

Date:	Sat, 22 Sep 2007 19:41:01 +0200
From:	Thomas Gleixner <tglx@...utronix.de>
To:	David Brownell <david-b@...bell.net>
Cc:	Andrew Morton <akpm@...l.org>, LKML <linux-kernel@...r.kernel.org>,
	Benedikt Spranger <bene@...utronix.de>,
	Stable Team <stable@...nel.org>
Subject: [PATCH] usb-gadget-ether: Prevent oops caused by error interrupt
	race -V2 (comments update)

From: Benedikt Spranger <bene@...utronix.de>
 
eth_start_xmit() can race against a disconnect interrupt in the gadget
device driver, which nukes all pending request. Right now we access the
pending request list unconditionally and dereference the request list
head itself in such a case, which results in an Oops.

Check whether the list is empty before actually dereferencing
dev->tx_reqs.next. Also add a comment for the second list_empty check
further down to avoid confusion.

Long standing bug. Patch should be applied to stable as well.

Signed-off-by: Benedikt Spranger <bene@...utronix.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>

diff --git a/drivers/usb/gadget/ether.c b/drivers/usb/gadget/ether.c
index 593e235..f2a7bd5 100644
--- a/drivers/usb/gadget/ether.c
+++ b/drivers/usb/gadget/ether.c
@@ -1989,8 +1989,21 @@ static int eth_start_xmit (struct sk_buff *skb, struct net_device *net)
 	}
 
 	spin_lock_irqsave(&dev->req_lock, flags);
+	/*
+	 * dev->tx_reqs may be empty. We raced against a disconnect
+	 * interrupt in the gadget device driver, which nuked all
+	 * pending requests.
+	 */
+	if (list_empty(&dev->tx_reqs)) {
+		netif_stop_queue(net);
+		spin_unlock_irqrestore(&dev->req_lock, flags);
+		return 1;
+	}
+
 	req = container_of (dev->tx_reqs.next, struct usb_request, list);
 	list_del (&req->list);
+
+	/* last request in list: stop queue */
 	if (list_empty (&dev->tx_reqs))
 		netif_stop_queue (net);
 	spin_unlock_irqrestore(&dev->req_lock, flags);


-
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/