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 AD1C2C433FE for ; Tue, 25 Jan 2022 19:55:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231142AbiAYTz2 (ORCPT ); Tue, 25 Jan 2022 14:55:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56742 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230488AbiAYTzZ (ORCPT ); Tue, 25 Jan 2022 14:55:25 -0500 Received: from mail-il1-x12e.google.com (mail-il1-x12e.google.com [IPv6:2607:f8b0:4864:20::12e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2F4DEC06173B; Tue, 25 Jan 2022 11:55:25 -0800 (PST) Received: by mail-il1-x12e.google.com with SMTP id w5so13573677ilo.2; Tue, 25 Jan 2022 11:55:25 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=date:from:to:cc:message-id:in-reply-to:references:subject :mime-version:content-transfer-encoding; bh=mwx4R51tDde945NwTITMzneq7WCyFOACKE0rm7tkswc=; b=jqLyFOBxbBXhtPgKrMFF+1wcWKHCyNfChGoR8WkBZxbYbQW0a0tsiYuzZG77QMF7wd phetNVLJcRps5G0f9jc8sMPmklJziKbtlIprJ7i/p2Fc5lCS85zTSvCQVJuTfLrxaAuI uh8I0qTmDmnr4lP5wU4Zv7/VOkwWugko98SEd5h4TfE5fO3p7tdByH3+sWN6H2ptgM6H oAaZT+GYQ4bQIEEjVE2oZaPa1RszBkK7V0af2g6FBLI8Pv2OcO47fgqWKi+cNqzEiEt3 3hDzwjjT3uNE/ajqs+WuWWvWi4JzJO2aGMzhPQiZJ9C+yyeMSWvngdqNnV+XGmzBQllL m+UQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:message-id:in-reply-to :references:subject:mime-version:content-transfer-encoding; bh=mwx4R51tDde945NwTITMzneq7WCyFOACKE0rm7tkswc=; b=a0gHJyUN1mqFsGJbOmItJFSjHjPqUBgMaUC0qa5gcSSFtAo5HyYDQtgZbNDNA6P8Ae xcPAtenkNqbeiP6+68Td6WjgubcGShyDCZuw/m5Jpz4gnBUUgm/hbNPvMs5gLIuUOPi+ uvNDusd//l5i8CTv172hbktkMIVWWbgT00gtIlTVlKmCYK1KTqpj2SiEkasFfYP/EFep r8+gWJh/vQJJ+FTIQXaP+NjTltOpVTI1+2we2b41k58Tt2JdXTf4VJ/YBCnlL2UWow7o xPOnZFk01oEug3qky0G40ds3XfasBrxReZSLERlM7F1co8CwAIbd0R9zT6DjPR56HmGc QBSQ== X-Gm-Message-State: AOAM530KKkrNLRXOHlrteGXVijeL8ZMVZnB53e6Rv5B79MLT2SHOnZs9 7+GmKKCbxPycfa8ohkxcBDs= X-Google-Smtp-Source: ABdhPJywhrD1lQyMvj4JDiOC9v80DY/8AHWvMwZslYWooJ6fPjdqAtqc8LGvmtNi/mDQmrvTfR9sZA== X-Received: by 2002:a05:6e02:1786:: with SMTP id y6mr12777811ilu.99.1643140524520; Tue, 25 Jan 2022 11:55:24 -0800 (PST) Received: from localhost ([99.197.200.79]) by smtp.gmail.com with ESMTPSA id q14sm2803192iow.1.2022.01.25.11.55.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 25 Jan 2022 11:55:24 -0800 (PST) Date: Tue, 25 Jan 2022 11:55:16 -0800 From: John Fastabend To: He Fengqing , ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, kafai@fb.com Cc: songliubraving@fb.com, yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org, netdev@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Message-ID: <61f055a4b6451_2e4c520871@john.notmuch> In-Reply-To: <20220122102936.1219518-1-hefengqing@huawei.com> References: <20220122102936.1219518-1-hefengqing@huawei.com> Subject: RE: [bpf-next] bpf: Fix possible race in inc_misses_counter Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org He Fengqing wrote: > It seems inc_misses_counter() suffers from same issue fixed in > the commit d979617aa84d ("bpf: Fixes possible race in update_prog_stats() > for 32bit arches"): > As it can run while interrupts are enabled, it could > be re-entered and the u64_stats syncp could be mangled. > > Fixes: 9ed9e9ba2337 ("bpf: Count the number of times recursion was prevented") > Signed-off-by: He Fengqing > --- > kernel/bpf/trampoline.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) Appears possible through sleepable progs. Acked-by: John Fastabend > diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c > index 4b6974a195c1..5e7edf913060 100644 > --- a/kernel/bpf/trampoline.c > +++ b/kernel/bpf/trampoline.c > @@ -550,11 +550,12 @@ static __always_inline u64 notrace bpf_prog_start_time(void) > static void notrace inc_misses_counter(struct bpf_prog *prog) > { > struct bpf_prog_stats *stats; > + unsigned int flags; > > stats = this_cpu_ptr(prog->stats); > - u64_stats_update_begin(&stats->syncp); > + flags = u64_stats_update_begin_irqsave(&stats->syncp); > u64_stats_inc(&stats->misses); > - u64_stats_update_end(&stats->syncp); > + u64_stats_update_end_irqrestore(&stats->syncp, flags); > } > > /* The logic is similar to bpf_prog_run(), but with an explicit > -- > 2.25.1 >