From patchwork Thu Jan 21 12:15:54 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steffen Klassert X-Patchwork-Id: 369302 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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 5A44DC433DB for ; Thu, 21 Jan 2021 12:19:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 09E1F221E2 for ; Thu, 21 Jan 2021 12:19:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730766AbhAUMTG (ORCPT ); Thu, 21 Jan 2021 07:19:06 -0500 Received: from a.mx.secunet.com ([62.96.220.36]:54612 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730832AbhAUMQu (ORCPT ); Thu, 21 Jan 2021 07:16:50 -0500 Received: from localhost (localhost [127.0.0.1]) by a.mx.secunet.com (Postfix) with ESMTP id 7F6B02027C; Thu, 21 Jan 2021 13:16:03 +0100 (CET) X-Virus-Scanned: by secunet Received: from a.mx.secunet.com ([127.0.0.1]) by localhost (a.mx.secunet.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ncZpjEadUzLw; Thu, 21 Jan 2021 13:16:02 +0100 (CET) Received: from mail-essen-01.secunet.de (unknown [10.53.40.204]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by a.mx.secunet.com (Postfix) with ESMTPS id 9216720322; Thu, 21 Jan 2021 13:16:02 +0100 (CET) Received: from mbx-essen-01.secunet.de (10.53.40.197) by mail-essen-01.secunet.de (10.53.40.204) with Microsoft SMTP Server (TLS) id 14.3.487.0; Thu, 21 Jan 2021 13:16:02 +0100 Received: from gauss2.secunet.de (10.182.7.193) by mbx-essen-01.secunet.de (10.53.40.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2044.4; Thu, 21 Jan 2021 13:16:02 +0100 Received: by gauss2.secunet.de (Postfix, from userid 1000) id 9BE353182BAE; Thu, 21 Jan 2021 13:16:01 +0100 (CET) From: Steffen Klassert To: David Miller , Jakub Kicinski CC: Herbert Xu , Steffen Klassert , Subject: [PATCH 1/5] xfrm: Fix oops in xfrm_replay_advance_bmp Date: Thu, 21 Jan 2021 13:15:54 +0100 Message-ID: <20210121121558.621339-2-steffen.klassert@secunet.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210121121558.621339-1-steffen.klassert@secunet.com> References: <20210121121558.621339-1-steffen.klassert@secunet.com> MIME-Version: 1.0 X-ClientProxiedBy: cas-essen-02.secunet.de (10.53.40.202) To mbx-essen-01.secunet.de (10.53.40.197) X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Shmulik Ladkani When setting xfrm replay_window to values higher than 32, a rare page-fault occurs in xfrm_replay_advance_bmp: BUG: unable to handle page fault for address: ffff8af350ad7920 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page PGD ad001067 P4D ad001067 PUD 0 Oops: 0002 [#1] SMP PTI CPU: 3 PID: 30 Comm: ksoftirqd/3 Kdump: loaded Not tainted 5.4.52-050452-generic #202007160732 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014 RIP: 0010:xfrm_replay_advance_bmp+0xbb/0x130 RSP: 0018:ffffa1304013ba40 EFLAGS: 00010206 RAX: 000000000000010d RBX: 0000000000000002 RCX: 00000000ffffff4b RDX: 0000000000000018 RSI: 00000000004c234c RDI: 00000000ffb3dbff RBP: ffffa1304013ba50 R08: ffff8af330ad7920 R09: 0000000007fffffa R10: 0000000000000800 R11: 0000000000000010 R12: ffff8af29d6258c0 R13: ffff8af28b95c700 R14: 0000000000000000 R15: ffff8af29d6258fc FS: 0000000000000000(0000) GS:ffff8af339ac0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffff8af350ad7920 CR3: 0000000015ee4000 CR4: 00000000001406e0 Call Trace: xfrm_input+0x4e5/0xa10 xfrm4_rcv_encap+0xb5/0xe0 xfrm4_udp_encap_rcv+0x140/0x1c0 Analysis revealed offending code is when accessing: replay_esn->bmp[nr] |= (1U << bitnr); with 'nr' being 0x07fffffa. This happened in an SMP system when reordering of packets was present; A packet arrived with a "too old" sequence number (outside the window, i.e 'diff > replay_window'), and therefore the following calculation: bitnr = replay_esn->replay_window - (diff - pos); yields a negative result, but since bitnr is u32 we get a large unsigned quantity (in crash dump above: 0xffffff4b seen in ecx). This was supposed to be protected by xfrm_input()'s former call to: if (x->repl->check(x, skb, seq)) { However, the state's spinlock x->lock is *released* after '->check()' is performed, and gets re-acquired before '->advance()' - which gives a chance for a different core to update the xfrm state, e.g. by advancing 'replay_esn->seq' when it encounters more packets - leading to a 'diff > replay_window' situation when original core continues to xfrm_replay_advance_bmp(). An attempt to fix this issue was suggested in commit bcf66bf54aab ("xfrm: Perform a replay check after return from async codepaths"), by calling 'x->repl->recheck()' after lock is re-acquired, but fix applied only to asyncronous crypto algorithms. Augment the fix, by *always* calling 'recheck()' - irrespective if we're using async crypto. Fixes: 0ebea8ef3559 ("[IPSEC]: Move state lock into x->type->input") Signed-off-by: Shmulik Ladkani Signed-off-by: Steffen Klassert --- net/xfrm/xfrm_input.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c index 37456d022cfa..61e6220ddd5a 100644 --- a/net/xfrm/xfrm_input.c +++ b/net/xfrm/xfrm_input.c @@ -660,7 +660,7 @@ int xfrm_input(struct sk_buff *skb, int nexthdr, __be32 spi, int encap_type) /* only the first xfrm gets the encap type */ encap_type = 0; - if (async && x->repl->recheck(x, skb, seq)) { + if (x->repl->recheck(x, skb, seq)) { XFRM_INC_STATS(net, LINUX_MIB_XFRMINSTATESEQERROR); goto drop_unlock; }