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 44882C4167B for ; Wed, 28 Dec 2022 15:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233856AbiL1Peo (ORCPT ); Wed, 28 Dec 2022 10:34:44 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233449AbiL1Pem (ORCPT ); Wed, 28 Dec 2022 10:34:42 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E55F915FF3 for ; Wed, 28 Dec 2022 07:34:41 -0800 (PST) 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 955ACB81647 for ; Wed, 28 Dec 2022 15:34:40 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E352EC433D2; Wed, 28 Dec 2022 15:34:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672241679; bh=dI78X4+JRfwLn7DLho4ytF6hGZAUmP8/pHSuFy7Fho0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QTAvxq9sfYbDiHh2Ojsv9+IuLPSb8syK8+iFz7I2IXCLuvrSkQzy519JymHkNc0DQ u61SGpe236SYQruwxJy2jwKr8zvu+Uf4BlhQL+FRYr6C0+kMDRd9FJTpOR6d83oIn6 XVd4+vO54JRrV+gE/Pa53FEWm4wCdlLgrWfRHX+Y= 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 6.1 0276/1146] bpf: Fix slot type check in check_stack_write_var_off Date: Wed, 28 Dec 2022 15:30:15 +0100 Message-Id: <20221228144337.632432018@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20221228144330.180012208@linuxfoundation.org> References: <20221228144330.180012208@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 f5e477a861e4a20d8a1c5f7a245f3a3c3c376b03 ] For the case where allow_ptr_leaks is false, code is checking whether slot type is STACK_INVALID and STACK_SPILL and rejecting other cases. This is a consequence of incorrectly checking for register type instead of the slot type (NOT_INIT and SCALAR_VALUE respectively). Fix the check. Fixes: 01f810ace9ed ("bpf: Allow variable-offset stack access") Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20221103191013.1236066-5-memxor@gmail.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- kernel/bpf/verifier.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 146056c79cc9..d533488b75c6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3186,14 +3186,17 @@ static int check_stack_write_var_off(struct bpf_verifier_env *env, stype = &state->stack[spi].slot_type[slot % BPF_REG_SIZE]; mark_stack_slot_scratched(env, spi); - if (!env->allow_ptr_leaks - && *stype != NOT_INIT - && *stype != SCALAR_VALUE) { - /* Reject the write if there's are spilled pointers in - * range. If we didn't reject here, the ptr status - * would be erased below (even though not all slots are - * actually overwritten), possibly opening the door to - * leaks. + if (!env->allow_ptr_leaks && *stype != STACK_MISC && *stype != STACK_ZERO) { + /* Reject the write if range we may write to has not + * been initialized beforehand. If we didn't reject + * here, the ptr status would be erased below (even + * though not all slots are actually overwritten), + * possibly opening the door to leaks. + * + * We do however catch STACK_INVALID case below, and + * only allow reading possibly uninitialized memory + * later for CAP_PERFMON, as the write may not happen to + * that slot. */ verbose(env, "spilled ptr in range of var-offset stack write; insn %d, ptr off: %d", insn_idx, i); -- 2.35.1