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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 81FA4C07E8D for ; Sun, 13 Aug 2023 21:48:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229736AbjHMVsT (ORCPT ); Sun, 13 Aug 2023 17:48:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41698 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229716AbjHMVro (ORCPT ); Sun, 13 Aug 2023 17:47:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 06BB12D54 for ; Sun, 13 Aug 2023 14:47:44 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 91C7A61468 for ; Sun, 13 Aug 2023 21:47:43 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1758C433C8; Sun, 13 Aug 2023 21:47:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1691963263; bh=KIQKBMxsxBm8ZivjrCUDcmkmZ727GIki3sXbx7Bs2l4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kC5wXyFfb4F6Gj9j4qtuCB4/97UQMWGQv+2nRDfPqV5DkOgwj/Rlm1vtj/h1bDioa n45ujVzh5jZTqCDt82NxwC7EpYi5AJet1hfK7bp9Fx9kxONjdPaDlAtKWY6svi7EZm llRMRnf91/lJ4uRMdOC2iEqGeIsh8FCzTs2lu9Z0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Andrew Kanner , Jakub Kicinski Subject: [PATCH 5.4 22/39] drivers: net: prevent tun_build_skb() to exceed the packet size limit Date: Sun, 13 Aug 2023 23:20:13 +0200 Message-ID: <20230813211705.582921376@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230813211704.796906808@linuxfoundation.org> References: <20230813211704.796906808@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Andrew Kanner commit 59eeb232940515590de513b997539ef495faca9a upstream. Using the syzkaller repro with reduced packet size it was discovered that XDP_PACKET_HEADROOM is not checked in tun_can_build_skb(), although pad may be incremented in tun_build_skb(). This may end up with exceeding the PAGE_SIZE limit in tun_build_skb(). Jason Wang proposed to count XDP_PACKET_HEADROOM always (e.g. without rcu_access_pointer(tun->xdp_prog)) in tun_can_build_skb() since there's a window during which XDP program might be attached between tun_can_build_skb() and tun_build_skb(). Fixes: 7df13219d757 ("tun: reserve extra headroom only when XDP is set") Link: https://syzkaller.appspot.com/bug?extid=f817490f5bd20541b90a Signed-off-by: Andrew Kanner Link: https://lore.kernel.org/r/20230803185947.2379988-1-andrew.kanner@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/tun.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1672,7 +1672,7 @@ static bool tun_can_build_skb(struct tun if (zerocopy) return false; - if (SKB_DATA_ALIGN(len + TUN_RX_PAD) + + if (SKB_DATA_ALIGN(len + TUN_RX_PAD + XDP_PACKET_HEADROOM) + SKB_DATA_ALIGN(sizeof(struct skb_shared_info)) > PAGE_SIZE) return false;