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 3888BC0015E for ; Tue, 25 Jul 2023 10:59:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232127AbjGYK7v (ORCPT ); Tue, 25 Jul 2023 06:59:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35770 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233795AbjGYK71 (ORCPT ); Tue, 25 Jul 2023 06:59:27 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2348A26BD for ; Tue, 25 Jul 2023 03:56:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7E95C61648 for ; Tue, 25 Jul 2023 10:56:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9206CC433C7; Tue, 25 Jul 2023 10:56:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690282580; bh=+WEF1LwouZ63dxdQ8qll2lQm/WA4SkTdlhGj/EPeibI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=b5KW6c0i9RlZlKlZ8wUKNkd0GyiBrtdQiA91wlwIn6md49qbMWgu++U2x7WEN893t ulPogPMYyak4KTwqft9K5PUihVtlI4ELG7Kj10EXA7py4mQm9UH84uPOxa4QoRfkUW dsERS/HA+1cywsYm2sssWIwBDMZAXJJPOx3GeQ50= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kumar Kartikeya Dwivedi , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.4 180/227] bpf: Fix subprog idx logic in check_max_stack_depth Date: Tue, 25 Jul 2023 12:45:47 +0200 Message-ID: <20230725104522.275834560@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104514.821564989@linuxfoundation.org> References: <20230725104514.821564989@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kumar Kartikeya Dwivedi [ Upstream commit ba7b3e7d5f9014be65879ede8fd599cb222901c9 ] The assignment to idx in check_max_stack_depth happens once we see a bpf_pseudo_call or bpf_pseudo_func. This is not an issue as the rest of the code performs a few checks and then pushes the frame to the frame stack, except the case of async callbacks. If the async callback case causes the loop iteration to be skipped, the idx assignment will be incorrect on the next iteration of the loop. The value stored in the frame stack (as the subprogno of the current subprog) will be incorrect. This leads to incorrect checks and incorrect tail_call_reachable marking. Save the target subprog in a new variable and only assign to idx once we are done with the is_async_cb check which may skip pushing of frame to the frame stack and subsequent stack depth checks and tail call markings. Fixes: 7ddc80a476c2 ("bpf: Teach stack depth check about async callbacks.") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20230717161530.1238-2-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index aac31e33323bb..e95bfe45fd890 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5429,7 +5429,7 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) continue_func: subprog_end = subprog[idx + 1].start; for (; i < subprog_end; i++) { - int next_insn; + int next_insn, sidx; if (!bpf_pseudo_call(insn + i) && !bpf_pseudo_func(insn + i)) continue; @@ -5439,14 +5439,14 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) /* find the callee */ next_insn = i + insn[i].imm + 1; - idx = find_subprog(env, next_insn); - if (idx < 0) { + sidx = find_subprog(env, next_insn); + if (sidx < 0) { WARN_ONCE(1, "verifier bug. No program starts at insn %d\n", next_insn); return -EFAULT; } - if (subprog[idx].is_async_cb) { - if (subprog[idx].has_tail_call) { + if (subprog[sidx].is_async_cb) { + if (subprog[sidx].has_tail_call) { verbose(env, "verifier bug. subprog has tail_call and async cb\n"); return -EFAULT; } @@ -5455,6 +5455,7 @@ static int check_max_stack_depth(struct bpf_verifier_env *env) continue; } i = next_insn; + idx = sidx; if (subprog[idx].has_tail_call) tail_call_reachable = true; -- 2.39.2