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 81C78CD13D8 for ; Sun, 17 Sep 2023 19:53:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240114AbjIQTxH (ORCPT ); Sun, 17 Sep 2023 15:53:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45792 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240182AbjIQTws (ORCPT ); Sun, 17 Sep 2023 15:52:48 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 09031195 for ; Sun, 17 Sep 2023 12:52:04 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3A900C433C9; Sun, 17 Sep 2023 19:52:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694980323; bh=59OISQo5yJm9nwZ+bUhiSNP5EokUGs98oC78DXua8lc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FipLwws+gCT8JLqBFked0Z0xCdt5giztplJSFS4ff+nAI/99Mp1huE7wJTFz2q87I /AyEAr08m/BrrFCUpngbhSEwfcUWGluA/6uKG1Lvv5eyktCvhCxkhSK+urJbBNYlp8 rQP7cJ5UB++NVgDzDs7A86WsC0DTUvvbO/kN8aQc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sebastian Andrzej Siewior , Daniel Borkmann , Jiri Olsa , Sasha Levin Subject: [PATCH 6.5 158/285] bpf: Assign bpf_tramp_run_ctx::saved_run_ctx before recursion check. Date: Sun, 17 Sep 2023 21:12:38 +0200 Message-ID: <20230917191057.146769732@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230917191051.639202302@linuxfoundation.org> References: <20230917191051.639202302@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sebastian Andrzej Siewior [ Upstream commit 6764e767f4af1e35f87f3497e1182d945de37f93 ] __bpf_prog_enter_recur() assigns bpf_tramp_run_ctx::saved_run_ctx before performing the recursion check which means in case of a recursion __bpf_prog_exit_recur() uses the previously set bpf_tramp_run_ctx::saved_run_ctx value. __bpf_prog_enter_sleepable_recur() assigns bpf_tramp_run_ctx::saved_run_ctx after the recursion check which means in case of a recursion __bpf_prog_exit_sleepable_recur() uses an uninitialized value. This does not look right. If I read the entry trampoline code right, then bpf_tramp_run_ctx isn't initialized upfront. Align __bpf_prog_enter_sleepable_recur() with __bpf_prog_enter_recur() and set bpf_tramp_run_ctx::saved_run_ctx before the recursion check is made. Remove the assignment of saved_run_ctx in kern_sys_bpf() since it happens a few cycles later. Fixes: e384c7b7b46d0 ("bpf, x86: Create bpf_tramp_run_ctx on the caller thread's stack") Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Daniel Borkmann Acked-by: Jiri Olsa Link: https://lore.kernel.org/bpf/20230830080405.251926-3-bigeasy@linutronix.de Signed-off-by: Sasha Levin --- kernel/bpf/syscall.c | 1 - kernel/bpf/trampoline.c | 5 ++--- 2 files changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index c925c270ed8b4..1480b6cf12f06 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5304,7 +5304,6 @@ int kern_sys_bpf(int cmd, union bpf_attr *attr, unsigned int size) } run_ctx.bpf_cookie = 0; - run_ctx.saved_run_ctx = NULL; if (!__bpf_prog_enter_sleepable_recur(prog, &run_ctx)) { /* recursion detected */ __bpf_prog_exit_sleepable_recur(prog, 0, &run_ctx); diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 78acf28d48732..53ff50cac61ea 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -926,13 +926,12 @@ u64 notrace __bpf_prog_enter_sleepable_recur(struct bpf_prog *prog, migrate_disable(); might_fault(); + run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); + if (unlikely(this_cpu_inc_return(*(prog->active)) != 1)) { bpf_prog_inc_misses_counter(prog); return 0; } - - run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); - return bpf_prog_start_time(); } -- 2.40.1