Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753387Ab3JUIuq (ORCPT ); Mon, 21 Oct 2013 04:50:46 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:39339 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753298Ab3JUIum (ORCPT ); Mon, 21 Oct 2013 04:50:42 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Roger Pau Monne" , "Matt Wilson" , "Konrad Rzeszutek Wilk" , "David Vrabel" Date: Mon, 21 Oct 2013 09:46:28 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 019/149] xen-gnt: prevent adding duplicate gnt callbacks In-Reply-To: X-SA-Exim-Connect-IP: 212.20.242.100 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1894 Lines: 57 3.2.52-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Roger Pau Monne commit 5f338d9001094a56cf87bd8a280b4e7ff953bb59 upstream. With the current implementation, the callback in the tail of the list can be added twice, because the check done in gnttab_request_free_callback is bogus, callback->next can be NULL if it is the last callback in the list. If we add the same callback twice we end up with an infinite loop, were callback == callback->next. Replace this check with a proper one that iterates over the list to see if the callback has already been added. Signed-off-by: Roger Pau Monné Cc: Konrad Rzeszutek Wilk Cc: David Vrabel Signed-off-by: Konrad Rzeszutek Wilk Acked-by: Matt Wilson Reviewed-by: David Vrabel Signed-off-by: Ben Hutchings --- drivers/xen/grant-table.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -355,9 +355,18 @@ void gnttab_request_free_callback(struct void (*fn)(void *), void *arg, u16 count) { unsigned long flags; + struct gnttab_free_callback *cb; + spin_lock_irqsave(&gnttab_list_lock, flags); - if (callback->next) - goto out; + + /* Check if the callback is already on the list */ + cb = gnttab_free_callback_list; + while (cb) { + if (cb == callback) + goto out; + cb = cb->next; + } + callback->fn = fn; callback->arg = arg; callback->count = count; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/