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=-8.4 required=3.0 tests=DKIM_ADSP_ALL,DKIM_INVALID, DKIM_SIGNED,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 5E545C43603 for ; Thu, 12 Dec 2019 12:38:07 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 307E221655 for ; Thu, 12 Dec 2019 12:38:07 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="ZOXWWasn" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 307E221655 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=amazon.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=xen-devel-bounces@lists.xenproject.org Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ifNj8-00088F-IU; Thu, 12 Dec 2019 12:37:54 +0000 Received: from us1-rack-iad1.inumbo.com ([172.99.69.81]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1ifNj6-000885-Mn for xen-devel@lists.xenproject.org; Thu, 12 Dec 2019 12:37:52 +0000 X-Inumbo-ID: 36417d6c-1cdc-11ea-b6f1-bc764e2007e4 Received: from smtp-fw-9101.amazon.com (unknown [207.171.184.25]) by us1-rack-iad1.inumbo.com (Halon) with ESMTPS id 36417d6c-1cdc-11ea-b6f1-bc764e2007e4; Thu, 12 Dec 2019 12:37:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1576154273; x=1607690273; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=64i9dOS4nNgwTFfSAmSWV7jMZ71ZQlmzTwYxEKBpjQc=; b=ZOXWWasnhBVeZxq7O0dUAJJ/VdHQEynkqNuDL+tL52AoxlOvxkIyQ5YO Fvo4nGHQMN+oW0v3voIDZW4H9jYRTe0RIV0DV7d76/9T7AjT+sebE35RK r2ey9TD4yaLjPgldkSmOruYAI4ZUj3OIxanSIb+VYwcswDHBsmQCPCI62 4=; IronPort-SDR: u48cjDvfsDaqvN8mi03+dtkm+PjjjAcd0TOEvApWEU4rNGoaDFBQwhsWz1lW0OSTr6EgStUtWO qWR9JC3DsDjA== X-IronPort-AV: E=Sophos;i="5.69,305,1571702400"; d="scan'208";a="4722440" Received: from sea32-co-svc-lb4-vlan3.sea.corp.amazon.com (HELO email-inbound-relay-1e-97fdccfd.us-east-1.amazon.com) ([10.47.23.38]) by smtp-border-fw-out-9101.sea19.amazon.com with ESMTP; 12 Dec 2019 12:37:39 +0000 Received: from EX13MTAUEA001.ant.amazon.com (iad55-ws-svc-p15-lb9-vlan3.iad.amazon.com [10.40.159.166]) by email-inbound-relay-1e-97fdccfd.us-east-1.amazon.com (Postfix) with ESMTPS id B8FDBA1CBF; Thu, 12 Dec 2019 12:37:36 +0000 (UTC) Received: from EX13D32EUB004.ant.amazon.com (10.43.166.212) by EX13MTAUEA001.ant.amazon.com (10.43.61.243) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 12 Dec 2019 12:37:36 +0000 Received: from EX13MTAUWA001.ant.amazon.com (10.43.160.58) by EX13D32EUB004.ant.amazon.com (10.43.166.212) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Thu, 12 Dec 2019 12:37:35 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.160.118) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Thu, 12 Dec 2019 12:37:32 +0000 From: Paul Durrant To: , , Date: Thu, 12 Dec 2019 12:37:23 +0000 Message-ID: <20191212123723.21548-1-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Precedence: Bulk Subject: [Xen-devel] [PATCH net] xen-netback: avoid race that can lead to NULL pointer dereference X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Paul Durrant , Jakub Kicinski , Wei Liu , "David S. Miller" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Q29tbWl0IDJhYzA2MWNlOTdmNCAoInhlbi9uZXRiYWNrOiBjbGVhbnVwIGluaXQgYW5kIGRlaW5p dCBjb2RlIikKaW50cm9kdWNlZCBhIHByb2JsZW0uIEluIGZ1bmN0aW9uIHhlbnZpZl9kaXNjb25u ZWN0X3F1ZXVlKCksIHRoZSB2YWx1ZSBvZgpxdWV1ZS0+cnhfaXJxIGlzIHplcm9lZCAqYmVmb3Jl KiBxdWV1ZS0+dGFzayBpcyBzdG9wcGVkLiBVbmZvcnR1bmF0ZWx5IHRoYXQKdGFzayBtYXkgY2Fs bCBub3RpZnlfcmVtb3RlX3ZpYV9pcnEocXVldWUtPnJ4X2lycSkgYW5kIGNhbGxpbmcgdGhhdApm dW5jdGlvbiB3aXRoIGEgemVybyB2YWx1ZSByZXN1bHRzIGluIGEgTlVMTCBwb2ludGVyIGRlcmVm ZXJlbmNlIGluCmV2dGNobl9mcm9tX2lycSgpLgoKVGhpcyBwYXRjaCBzaW1wbHkgcmUtb3JkZXJz IHRoaW5ncywgc3RvcHBpbmcgYWxsIHRhc2tzIGJlZm9yZSB6ZXJvLWluZyB0aGUKaXJxIHZhbHVl cywgdGhlcmVieSBhdm9pZGluZyB0aGUgcG9zc2liaWxpdHkgb2YgdGhlIHJhY2UuCgpTaWduZWQt b2ZmLWJ5OiBQYXVsIER1cnJhbnQgPHBkdXJyYW50QGFtYXpvbi5jb20+Ci0tLQpDYzogSnVlcmdl biBHcm9zcyA8amdyb3NzQHN1c2UuY29tPgpDYzogSmFrdWIgS2ljaW5za2kgPGpha3ViLmtpY2lu c2tpQG5ldHJvbm9tZS5jb20+CkNjOiBXZWkgTGl1IDx3ZWkubGl1QGtlcm5lbC5vcmc+CkNjOiAi RGF2aWQgUy4gTWlsbGVyIiA8ZGF2ZW1AZGF2ZW1sb2Z0Lm5ldD4KLS0tCiBkcml2ZXJzL25ldC94 ZW4tbmV0YmFjay9pbnRlcmZhY2UuYyB8IDI0ICsrKysrKysrKysrKy0tLS0tLS0tLS0tLQogMSBm aWxlIGNoYW5nZWQsIDEyIGluc2VydGlvbnMoKyksIDEyIGRlbGV0aW9ucygtKQoKZGlmZiAtLWdp dCBhL2RyaXZlcnMvbmV0L3hlbi1uZXRiYWNrL2ludGVyZmFjZS5jIGIvZHJpdmVycy9uZXQveGVu LW5ldGJhY2svaW50ZXJmYWNlLmMKaW5kZXggNjhkZDdiYjA3Y2E2Li5mMTViYTNkZTYxOTUgMTAw NjQ0Ci0tLSBhL2RyaXZlcnMvbmV0L3hlbi1uZXRiYWNrL2ludGVyZmFjZS5jCisrKyBiL2RyaXZl cnMvbmV0L3hlbi1uZXRiYWNrL2ludGVyZmFjZS5jCkBAIC02MjgsMTggKzYyOCw2IEBAIGludCB4 ZW52aWZfY29ubmVjdF9jdHJsKHN0cnVjdCB4ZW52aWYgKnZpZiwgZ3JhbnRfcmVmX3QgcmluZ19y ZWYsCiAKIHN0YXRpYyB2b2lkIHhlbnZpZl9kaXNjb25uZWN0X3F1ZXVlKHN0cnVjdCB4ZW52aWZf cXVldWUgKnF1ZXVlKQogewotCWlmIChxdWV1ZS0+dHhfaXJxKSB7Ci0JCXVuYmluZF9mcm9tX2ly cWhhbmRsZXIocXVldWUtPnR4X2lycSwgcXVldWUpOwotCQlpZiAocXVldWUtPnR4X2lycSA9PSBx dWV1ZS0+cnhfaXJxKQotCQkJcXVldWUtPnJ4X2lycSA9IDA7Ci0JCXF1ZXVlLT50eF9pcnEgPSAw OwotCX0KLQotCWlmIChxdWV1ZS0+cnhfaXJxKSB7Ci0JCXVuYmluZF9mcm9tX2lycWhhbmRsZXIo cXVldWUtPnJ4X2lycSwgcXVldWUpOwotCQlxdWV1ZS0+cnhfaXJxID0gMDsKLQl9Ci0KIAlpZiAo cXVldWUtPnRhc2spIHsKIAkJa3RocmVhZF9zdG9wKHF1ZXVlLT50YXNrKTsKIAkJcXVldWUtPnRh c2sgPSBOVUxMOwpAQCAtNjU1LDYgKzY0MywxOCBAQCBzdGF0aWMgdm9pZCB4ZW52aWZfZGlzY29u bmVjdF9xdWV1ZShzdHJ1Y3QgeGVudmlmX3F1ZXVlICpxdWV1ZSkKIAkJcXVldWUtPm5hcGkucG9s bCA9IE5VTEw7CiAJfQogCisJaWYgKHF1ZXVlLT50eF9pcnEpIHsKKwkJdW5iaW5kX2Zyb21faXJx aGFuZGxlcihxdWV1ZS0+dHhfaXJxLCBxdWV1ZSk7CisJCWlmIChxdWV1ZS0+dHhfaXJxID09IHF1 ZXVlLT5yeF9pcnEpCisJCQlxdWV1ZS0+cnhfaXJxID0gMDsKKwkJcXVldWUtPnR4X2lycSA9IDA7 CisJfQorCisJaWYgKHF1ZXVlLT5yeF9pcnEpIHsKKwkJdW5iaW5kX2Zyb21faXJxaGFuZGxlcihx dWV1ZS0+cnhfaXJxLCBxdWV1ZSk7CisJCXF1ZXVlLT5yeF9pcnEgPSAwOworCX0KKwogCXhlbnZp Zl91bm1hcF9mcm9udGVuZF9kYXRhX3JpbmdzKHF1ZXVlKTsKIH0KIAotLSAKMi4yMC4xCgoKX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVsIG1h aWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0cy54 ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== 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=-9.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 CD39BC2D0CA for ; 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Thu, 12 Dec 2019 12:37:32 +0000 From: Paul Durrant To: , , CC: Paul Durrant , Juergen Gross , "Jakub Kicinski" , Wei Liu , "David S. Miller" Subject: [PATCH net] xen-netback: avoid race that can lead to NULL pointer dereference Date: Thu, 12 Dec 2019 12:37:23 +0000 Message-ID: <20191212123723.21548-1-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 2ac061ce97f4 ("xen/netback: cleanup init and deinit code") introduced a problem. In function xenvif_disconnect_queue(), the value of queue->rx_irq is zeroed *before* queue->task is stopped. Unfortunately that task may call notify_remote_via_irq(queue->rx_irq) and calling that function with a zero value results in a NULL pointer dereference in evtchn_from_irq(). This patch simply re-orders things, stopping all tasks before zero-ing the irq values, thereby avoiding the possibility of the race. Signed-off-by: Paul Durrant --- Cc: Juergen Gross Cc: Jakub Kicinski Cc: Wei Liu Cc: "David S. Miller" --- drivers/net/xen-netback/interface.c | 24 ++++++++++++------------ 1 file changed, 12 insertions(+), 12 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index 68dd7bb07ca6..f15ba3de6195 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -628,18 +628,6 @@ int xenvif_connect_ctrl(struct xenvif *vif, grant_ref_t ring_ref, static void xenvif_disconnect_queue(struct xenvif_queue *queue) { - if (queue->tx_irq) { - unbind_from_irqhandler(queue->tx_irq, queue); - if (queue->tx_irq == queue->rx_irq) - queue->rx_irq = 0; - queue->tx_irq = 0; - } - - if (queue->rx_irq) { - unbind_from_irqhandler(queue->rx_irq, queue); - queue->rx_irq = 0; - } - if (queue->task) { kthread_stop(queue->task); queue->task = NULL; @@ -655,6 +643,18 @@ static void xenvif_disconnect_queue(struct xenvif_queue *queue) queue->napi.poll = NULL; } + if (queue->tx_irq) { + unbind_from_irqhandler(queue->tx_irq, queue); + if (queue->tx_irq == queue->rx_irq) + queue->rx_irq = 0; + queue->tx_irq = 0; + } + + if (queue->rx_irq) { + unbind_from_irqhandler(queue->rx_irq, queue); + queue->rx_irq = 0; + } + xenvif_unmap_frontend_data_rings(queue); } -- 2.20.1