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 4C7CB398; Fri, 18 Aug 2023 02:10:42 +0000 (UTC) Received: from mail-pf1-x432.google.com (mail-pf1-x432.google.com [IPv6:2607:f8b0:4864:20::432]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 73EAC30FE; Thu, 17 Aug 2023 19:10:41 -0700 (PDT) Received: by mail-pf1-x432.google.com with SMTP id d2e1a72fcca58-689e6fce70dso387546b3a.1; Thu, 17 Aug 2023 19:10:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1692324641; x=1692929441; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=Wsj2zNj3xkOCvdWvIxiq3aCWKIVsXzUeqck+9IunsAc=; b=jHlL0o0V1LTQeWAo+KNlFfRAv/jd6lTaog8cCSKfDTDEwHOrkaTqcPmoUmqRJBJjls lZBL8YRCVda8i+gbzx816gCP7Sib/Ek+8MvlP5aDXSNmo9vncFdWDfQl8RiWsCMpl125 JpK7jG+A93A8bO36o0hQybAkud2Xf8AdSRijcTWLpr6I6ms83Ja9ANwehcp3s1zdxZIQ uNSDYtGfmxVJ3LINfFmA/DkciALcdfU6W6yd6wjvvt9Vjm6JdRF1ZQCt7QNWpAK7d3xB vFbcQGr+qItjkOtnK23pyxVCOKVjsPSAjC9v+QV15VTKz+8FjJbN3+OZAxGXnG0U7kRm 1f/Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692324641; x=1692929441; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Wsj2zNj3xkOCvdWvIxiq3aCWKIVsXzUeqck+9IunsAc=; b=O8b2KmrfXN0rKVY2WVP+6Iys9kalHJ9tGAIvKi1EBlJc6ImvLOnY/TI1UVt+h/xGwL N8AnP4uglqARk7U62PB8CdcvKVlIeWR8U4rovQm4Hd5Tm0GMIUS5nzsTAF2etqpzE37M t3Zai0feOx780+EqD/fLHwL5/j1kuHipzGdk6Wp1Rz9vwCMpFRfJXSy+ri75qxhA5CiJ x2wWGtVs8QefRBaNatfpw9UdjlXlsH/AiyRaa3eQS/wFueMsvrHnQZTmGsKt2OAsJ0wr t1a/IU56dIINWnk7+85javWa2oBnZwbZGHe3L93cSZ5i/onjslxNu2bZ/ZiOYFJIzB+9 2GCw== X-Gm-Message-State: AOJu0Yzvca/Shk+hj2W3E1EMwAQdhwn/Kme90yJBGuetfl57AQ+uhleU SF4ha1TJAqoGXlAGBnicQMo= X-Google-Smtp-Source: AGHT+IGuSeE4KmfNgan/3FH0662SMQS1YQkxWfN4l4PzfLryD1ZsnCd7EuNnUHT56oa64CZ8k00oaQ== X-Received: by 2002:a05:6a00:134a:b0:687:e02b:e3c with SMTP id k10-20020a056a00134a00b00687e02b0e3cmr1630698pfu.17.1692324640752; Thu, 17 Aug 2023 19:10:40 -0700 (PDT) Received: from [10.22.68.146] ([122.11.166.8]) by smtp.gmail.com with ESMTPSA id n22-20020a62e516000000b006870ccfbb54sm400622pff.196.2023.08.17.19.10.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 17 Aug 2023 19:10:40 -0700 (PDT) Message-ID: Date: Fri, 18 Aug 2023 10:10:33 +0800 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.14.0 Subject: Re: [RFC PATCH bpf-next 1/2] bpf, x64: Fix tailcall infinite loop bug Content-Language: en-US To: Alexei Starovoitov Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@google.com, haoluo@google.com, jolsa@kernel.org, x86@kernel.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, mykolal@fb.com, shuah@kernel.org, davem@davemloft.net, dsahern@kernel.org, tangyeechou@gmail.com, kernel-patches-bot@fb.com, maciej.fijalkowski@intel.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: <20230814134147.70289-1-hffilwlqm@gmail.com> <20230814134147.70289-2-hffilwlqm@gmail.com> <20230817223143.jyclrtf3a6kmtgh5@macbook-pro-8.dhcp.thefacebook.com> From: Leon Hwang In-Reply-To: <20230817223143.jyclrtf3a6kmtgh5@macbook-pro-8.dhcp.thefacebook.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=-6.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,HK_RANDOM_ENVFROM, HK_RANDOM_FROM,NICE_REPLY_A,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net On 18/8/23 06:31, Alexei Starovoitov wrote: > On Mon, Aug 14, 2023 at 09:41:46PM +0800, Leon Hwang wrote: >> @@ -1147,6 +1152,7 @@ struct bpf_attach_target_info { >> struct module *tgt_mod; >> const char *tgt_name; >> const struct btf_type *tgt_type; >> + bool tail_call_ctx; > > Instead of extra flag here can you check tgt_prog->aux->tail_call_reachable in check_attach_btf_id() > and set tr->flags there? Should we check tgt_prog->aux->func[subprog]->is_func? Or, tgt_prog->aux->tail_call_reachable is enough? I think tgt_prog->aux->func[subprog]->is_func is required to check. It's because it's a bug about subprog instead of tgt_prog. In check_attach_btf_id(): bool tail_call_ctx; // ... ret = bpf_check_attach_target(&env->log, prog, tgt_prog, btf_id, &tgt_info, &tail_call_ctx); // ... tr->flags = (tail_call_ctx ? BPF_TRAMP_F_TAIL_CALL_CTX : 0); How about changing like this? However, it's bad to change bpf_check_attach_target() declaration. > Other than this the fix makes sense. > Please trim your cc list when you respin.> Just maintainers, Maciej (author of fixes tag) and bpf@vger is enough. I'll trim it. Thanks, Leon