From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07566C4332D for ; Thu, 19 Mar 2020 07:14:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CA45D20409 for ; Thu, 19 Mar 2020 07:14:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726989AbgCSHOi (ORCPT ); Thu, 19 Mar 2020 03:14:38 -0400 Received: from mx2.suse.de ([195.135.220.15]:52010 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbgCSHOi (ORCPT ); Thu, 19 Mar 2020 03:14:38 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 01FE1ABDC; Thu, 19 Mar 2020 07:14:35 +0000 (UTC) From: Juergen Gross To: xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org Cc: Juergen Gross , Boris Ostrovsky , Stefano Stabellini , =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= , stable@vger.kernel.org Subject: [PATCH] xen/events: avoid NULL pointer dereference in evtchn_from_irq() Date: Thu, 19 Mar 2020 08:14:28 +0100 Message-Id: <20200319071428.12115-1-jgross@suse.com> X-Mailer: git-send-email 2.16.4 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org There have been reports of races in evtchn_from_irq() where the info pointer has been NULL. Avoid that case by testing info before dereferencing it. In order to avoid accessing a just freed info structure do the kfree() via kfree_rcu(). Cc: Marek Marczykowski-Górecki Cc: stable@vger.kernel.org Reported-by: Marek Marczykowski-Górecki Signed-off-by: Juergen Gross --- drivers/xen/events/events_base.c | 10 ++++++++-- drivers/xen/events/events_internal.h | 3 +++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/drivers/xen/events/events_base.c b/drivers/xen/events/events_base.c index 499eff7d3f65..838762fe3d6e 100644 --- a/drivers/xen/events/events_base.c +++ b/drivers/xen/events/events_base.c @@ -247,10 +247,16 @@ static void xen_irq_info_cleanup(struct irq_info *info) */ unsigned int evtchn_from_irq(unsigned irq) { + struct irq_info *info; + if (WARN(irq >= nr_irqs, "Invalid irq %d!\n", irq)) return 0; - return info_for_irq(irq)->evtchn; + info = info_for_irq(irq); + if (info == NULL) + return 0; + + return info->evtchn; } unsigned irq_from_evtchn(unsigned int evtchn) @@ -436,7 +442,7 @@ static void xen_free_irq(unsigned irq) WARN_ON(info->refcnt > 0); - kfree(info); + kfree_rcu(info, rcu); /* Legacy IRQ descriptors are managed by the arch. */ if (irq < nr_legacy_irqs()) diff --git a/drivers/xen/events/events_internal.h b/drivers/xen/events/events_internal.h index 82938cff6c7a..c421055843c8 100644 --- a/drivers/xen/events/events_internal.h +++ b/drivers/xen/events/events_internal.h @@ -7,6 +7,8 @@ #ifndef __EVENTS_INTERNAL_H__ #define __EVENTS_INTERNAL_H__ +#include + /* Interrupt types. */ enum xen_irq_type { IRQT_UNBOUND = 0, @@ -30,6 +32,7 @@ enum xen_irq_type { */ struct irq_info { struct list_head list; + struct rcu_head rcu; int refcnt; enum xen_irq_type type; /* type */ unsigned irq; -- 2.16.4