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 D543EC001DE for ; Wed, 26 Jul 2023 12:26:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233450AbjGZM0T (ORCPT ); Wed, 26 Jul 2023 08:26:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38390 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233722AbjGZM0Q (ORCPT ); Wed, 26 Jul 2023 08:26:16 -0400 Received: from mail-ej1-x62a.google.com (mail-ej1-x62a.google.com [IPv6:2a00:1450:4864:20::62a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93B362698 for ; Wed, 26 Jul 2023 05:26:09 -0700 (PDT) Received: by mail-ej1-x62a.google.com with SMTP id a640c23a62f3a-99bcc0adab4so62445266b.2 for ; Wed, 26 Jul 2023 05:26:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; t=1690374368; x=1690979168; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:from:to:cc:subject:date:message-id:reply-to; bh=Zw4DRcroK7b/Ks1g/UthzcdQpwOmLzE3yDyhD4mJ/48=; b=NRctkvSKs+iRsVWTOZqB7gngDEnfK/LWaunoUHDqBmsl8zHpvn2iWS36/Od0sBmlP5 bgEFSxuRPtraPIqqbylltCq6p74DT34dqQ8CENZ7S2I/+5XFdRzWfZmSjBqVQSKZctZk Pzv6HO/hLOX962lGP2VFYRYV5W4djxSgMgugU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1690374368; x=1690979168; h=mime-version:message-id:in-reply-to:date:subject:cc:to:from :user-agent:references:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Zw4DRcroK7b/Ks1g/UthzcdQpwOmLzE3yDyhD4mJ/48=; b=Eqo5xJ7G/2wDDzSV15kSO0UNEe0fkvciFry7lcoVOfrPGe1uyp1ecFbTIBf9tPquVm eSckCdyPeIfN1YxObG03Whywevb36dTAf5x8hQb6iunTOYCNcW5yGmeIFkUtP6lry6hu tdauVlyLvw4MwgF9YBHnPuw/BqH6bmDzgF79lq/CMtMDPwqRo9KpgUOPOm2lep6dFspP FVjzJqREzYE6FOOPISiR1Qc7punRWa+R4PcLkiFwPcN56CSTt+4BGE4u+O+kbUDsuyo8 MFw3iqMFPUXbzZf0bzKRwkt3C3E/+oYmw+5F2VN8912/iASSaZK0PTYwvOot7LJuznhE rTig== X-Gm-Message-State: ABy/qLZdzF910i/0jPnRtfkT0ats9mKTDw3Sqn9ErtmsNZIL1tKfsAoV GMYvgNbUtH/XMSs0BExvXMgJQw== X-Google-Smtp-Source: APBJJlGUuhYIKX/FLcEg4ECj+YQkaLws6RHjkPmrOYhV3X8HJknZffmI3n4yRUjOAgIU0PfTwQlETw== X-Received: by 2002:a17:907:a049:b0:994:54e7:1287 with SMTP id gz9-20020a170907a04900b0099454e71287mr1478975ejc.73.1690374367751; Wed, 26 Jul 2023 05:26:07 -0700 (PDT) Received: from cloudflare.com (79.184.136.135.ipv4.supernova.orange.pl. [79.184.136.135]) by smtp.gmail.com with ESMTPSA id n13-20020a170906378d00b0099b4ec39a19sm9621112ejc.6.2023.07.26.05.26.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jul 2023 05:26:07 -0700 (PDT) References: User-agent: mu4e 1.6.10; emacs 28.2 From: Jakub Sitnicki To: Yan Zhai Cc: bpf@vger.kernel.org, Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Mykola Lysenko , Shuah Khan , linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-kselftest@vger.kernel.org, kernel-team@cloudflare.com, Jordan Griege , Markus Elfring Subject: Re: [PATCH v4 bpf 1/2] bpf: fix skb_do_redirect return values Date: Wed, 26 Jul 2023 14:25:38 +0200 In-reply-to: Message-ID: <87ila6yi3l.fsf@cloudflare.com> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jul 25, 2023 at 06:08 PM -07, Yan Zhai wrote: > skb_do_redirect returns various of values: error code (negative), > 0 (success), and some positive status code, e.g. NET_XMIT_CN, > NET_RX_DROP. Commit 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel > infrastructure") didn't check the return code correctly, so positive > values are propagated back along call chain: > > ip_finish_output2 > -> bpf_xmit > -> run_lwt_bpf > -> skb_do_redirect > > Inside ip_finish_output2, redirected skb will continue to neighbor > subsystem as if LWTUNNEL_XMIT_CONTINUE is returned, despite that this > skb could have been freed. The bug can trigger use-after-free warning > and crashes kernel afterwards: > > https://gist.github.com/zhaiyan920/8fbac245b261fe316a7ef04c9b1eba48 > > Convert positive statuses from skb_do_redirect eliminates this issue. > > Fixes: 3a0af8fd61f9 ("bpf: BPF for lightweight tunnel infrastructure") > Tested-by: Jakub Sitnicki > Suggested-by: Markus Elfring > Suggested-by: Stanislav Fomichev > Reported-by: Jordan Griege > Signed-off-by: Yan Zhai > --- Reviewed-by: Jakub Sitnicki