From patchwork Wed Aug 30 16:29:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Eric Dumazet X-Patchwork-Id: 807699 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=gmail.com header.i=@gmail.com header.b="EWa9D0dN"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3xj9vP3TyRz9sNn for ; Thu, 31 Aug 2017 02:29:37 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751877AbdH3Q3f (ORCPT ); Wed, 30 Aug 2017 12:29:35 -0400 Received: from mail-pf0-f193.google.com ([209.85.192.193]:35059 "EHLO mail-pf0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751416AbdH3Q3e (ORCPT ); Wed, 30 Aug 2017 12:29:34 -0400 Received: by mail-pf0-f193.google.com with SMTP id g13so4622435pfm.2 for ; Wed, 30 Aug 2017 09:29:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=message-id:subject:from:to:cc:date:mime-version :content-transfer-encoding; bh=KWSObgh4UFR0v0MlZVL+hGXpgziTJQsvg8kSh3k+mSk=; b=EWa9D0dNTxqalwzxJnwUd9AGPTm5kwuxiZovdLwunplsH1+blo7w+UtVapyEsNvOuF TeJ7kBlzIem3l1Xju6j2zUVrKs0dSkq5CqKKCsJuJ7POqOn3+Xs02UlJ+fOBNU/Glf1B jA4eVWpvfiX2BHxnlBKopnB1CwO/WsVi+04tOxjP1V8UcotRDl6IyO/gJVr47mtHbhrq EEdkY8b3BvHAOAX9Ms7iXRdba6qjiO0b6ISkb2Am5PCuidxtFEKKuyA6DxpBN+uxNM+2 8ZtSGZXHEnPRl8DFsZGmKX4nhrAC9HcgoTe3f0ivAw/KXrjUs1MGKNLhzlQsiO0WivZ8 maaQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:mime-version :content-transfer-encoding; bh=KWSObgh4UFR0v0MlZVL+hGXpgziTJQsvg8kSh3k+mSk=; b=FEWYZWxE/xFDCzVTqKwvnFsGC03L7x6rK8z2CVnZ9m1HRhZpekyn7vnUyBi8R2vOjO KdsVp0eYb9quTjKOGdimdYdqmsHLa2Avebx255TgWATjigHn9cWg9S8OZkTFn8ygTle7 j0F495iu+lw7yynJsW4gD3z9+Fh9BqY5d5j8ah9VqTf+6ZbJddOftfwL1lGHjeMrLY5l W/Tg43VzhOUurunkhAvM7MfF+V6iFhFJdcStKzbQjs779WoKEVUOn67+APBOs64uvGyE /cSfQvJKKtMMHu4ud/t0ViWLr2KESS+W6Nb+AQYrVbY4GJlQYpZ5PMrHW+P3ETrgFVaU dFJQ== X-Gm-Message-State: AHYfb5iHLj8gVbovEY/Qez1GdkdWl3vd1zNVy7HYHDzsRxZMExx7zRL0 8s1Uvk4wi0RNW86b X-Received: by 10.84.236.2 with SMTP id q2mr2694253plk.317.1504110573591; Wed, 30 Aug 2017 09:29:33 -0700 (PDT) Received: from ?IPv6:2620:15c:2c1:100:dc1f:953d:4193:6c45? ([2620:15c:2c1:100:dc1f:953d:4193:6c45]) by smtp.googlemail.com with ESMTPSA id q66sm9710388pfb.132.2017.08.30.09.29.32 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 30 Aug 2017 09:29:32 -0700 (PDT) Message-ID: <1504110571.11498.120.camel@edumazet-glaptop3.roam.corp.google.com> Subject: [PATCH net] kcm: do not attach PF_KCM sockets to avoid deadlock From: Eric Dumazet To: David Miller Cc: netdev , Tom Herbert Date: Wed, 30 Aug 2017 09:29:31 -0700 X-Mailer: Evolution 3.10.4-0ubuntu2 Mime-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Eric Dumazet syzkaller had no problem to trigger a deadlock, attaching a KCM socket to another one (or itself). (original syzkaller report was a very confusing lockdep splat during a sendmsg()) It seems KCM claims to only support TCP, but no enforcement is done, so we might need to add additional checks. Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module") Signed-off-by: Eric Dumazet Reported-by: Dmitry Vyukov Acked-by: Tom Herbert --- net/kcm/kcmsock.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c index 48e993b2dbcf1afae04968ed840e2e98c2cf6772..af4e76ac88ff0817398d1d7460a41f0cd5fe6f30 100644 --- a/net/kcm/kcmsock.c +++ b/net/kcm/kcmsock.c @@ -1387,6 +1387,10 @@ static int kcm_attach(struct socket *sock, struct socket *csock, if (!csk) return -EINVAL; + /* We must prevent loops or risk deadlock ! */ + if (csk->sk_family == PF_KCM) + return -EOPNOTSUPP; + psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL); if (!psock) return -ENOMEM;