From nobody Fri Oct 17 10:32:17 2025 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 CA701C433FE for ; Wed, 19 Oct 2022 13:58:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230130AbiJSN6b (ORCPT ); Wed, 19 Oct 2022 09:58:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39882 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234010AbiJSNyf (ORCPT ); Wed, 19 Oct 2022 09:54:35 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A41AC1DDC1D; Wed, 19 Oct 2022 06:37:14 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 081FAB82337; Wed, 19 Oct 2022 08:49:48 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6BF7FC433D7; Wed, 19 Oct 2022 08:49:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666169386; bh=wQ4vvWEZ6w/RYnBZK7uYJgLompeNljXKcXo+SrdSuZc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vZJOy68sTzVZ5fdyI9kWgap0R8lusm9AulZ5eG6Y2yMIX+dzLJqA6FYkmXMG0d6pJ LZxURLjj4n8MSCe68VqLpWzKbJ+wnGbZv1maBD191kSWxowKyAEV3KqDciBP5C0Jga BrE+xmClkyuA+DI3dpwgB5R/B/+IXXzlqr3Ev7u4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hou Tao , Alexei Starovoitov , Martin KaFai Lau , Sasha Levin Subject: [PATCH 6.0 257/862] bpf: Use this_cpu_{inc_return|dec} for prog->active Date: Wed, 19 Oct 2022 10:25:44 +0200 Message-Id: <20221019083301.406438627@linuxfoundation.org> X-Mailer: git-send-email 2.38.0 In-Reply-To: <20221019083249.951566199@linuxfoundation.org> References: <20221019083249.951566199@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Hou Tao [ Upstream commit c89e843a11f1075d27684f6b42256213e4592383 ] Both __this_cpu_inc_return() and __this_cpu_dec() are not preemption safe and now migrate_disable() doesn't disable preemption, so the update of prog-active is not atomic and in theory under fully preemptible kernel recurisve prevention may do not work. Fixing by using the preemption-safe and IRQ-safe variants. Fixes: ca06f55b9002 ("bpf: Add per-program recursion prevention mechanism") Signed-off-by: Hou Tao Acked-by: Alexei Starovoitov Link: https://lore.kernel.org/r/20220901061938.3789460-3-houtao@huaweicloud= .com Signed-off-by: Martin KaFai Lau Signed-off-by: Sasha Levin --- kernel/bpf/trampoline.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index ff87e38af8a7..ad76940b02cc 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -895,7 +895,7 @@ u64 notrace __bpf_prog_enter(struct bpf_prog *prog, str= uct bpf_tramp_run_ctx *ru =20 run_ctx->saved_run_ctx =3D bpf_set_run_ctx(&run_ctx->run_ctx); =20 - if (unlikely(__this_cpu_inc_return(*(prog->active)) !=3D 1)) { + if (unlikely(this_cpu_inc_return(*(prog->active)) !=3D 1)) { inc_misses_counter(prog); return 0; } @@ -930,7 +930,7 @@ void notrace __bpf_prog_exit(struct bpf_prog *prog, u64= start, struct bpf_tramp_ bpf_reset_run_ctx(run_ctx->saved_run_ctx); =20 update_prog_stats(prog, start); - __this_cpu_dec(*(prog->active)); + this_cpu_dec(*(prog->active)); migrate_enable(); rcu_read_unlock(); } @@ -966,7 +966,7 @@ u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog = *prog, struct bpf_tramp_r migrate_disable(); might_fault(); =20 - if (unlikely(__this_cpu_inc_return(*(prog->active)) !=3D 1)) { + if (unlikely(this_cpu_inc_return(*(prog->active)) !=3D 1)) { inc_misses_counter(prog); return 0; } @@ -982,7 +982,7 @@ void notrace __bpf_prog_exit_sleepable(struct bpf_prog = *prog, u64 start, bpf_reset_run_ctx(run_ctx->saved_run_ctx); =20 update_prog_stats(prog, start); - __this_cpu_dec(*(prog->active)); + this_cpu_dec(*(prog->active)); migrate_enable(); rcu_read_unlock_trace(); } --=20 2.35.1