From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0AA65C153 for ; Wed, 26 Jul 2023 12:26:17 +0000 (UTC) Received: from mail-ej1-x636.google.com (mail-ej1-x636.google.com [IPv6:2a00:1450:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 93F2B26BE for ; Wed, 26 Jul 2023 05:26:09 -0700 (PDT) Received: by mail-ej1-x636.google.com with SMTP id a640c23a62f3a-99bcc0adab4so62444866b.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=ffkkRVS3V5FUBwJ2Sr99Ir7RC/8EQuOWkv1rY2mNIGbeEsL+0VoSRjEUjuVG3eOssU Fa+5SS7PF/4iIthzRQ1cSAYHD2Z2C8MsomX2I82+LIzTVJc2yyH+DVjf+LEl138ucCGH UB7EcWZbLTxj3gBS0V8d5L/2oSRLFqWYMEZaSMk/byfzU/4otJbs2fQXpcGFLhgf8a0r pSoDOTSjRkxBcYKrEll6WC7vPiuXzVOYvyxnyZ19fHqFtjU470p7mKd6DZ/AEidQ1yTa 70AouQGYRW+2P8zc6jAM47zhtuLd/O48xYF6W6hjfELXDspLYu9QPOJDWEl2+/FymXph wCAg== X-Gm-Message-State: ABy/qLYwxGgJ4Lwzn4Rbwl1mg8/NkIj3mgAhmHbAGliV15+4PM95XGXL 6lJyAYuOzBMmlwWE2qFK0iiKbw== 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> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE, SPF_HELO_NONE,SPF_NONE,T_SCC_BODY_TEXT_LINE,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net 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