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 X-Spam-Level: X-Spam-Status: No, score=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A81EBC43381 for ; Mon, 1 Apr 2019 17:19:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F3B920883 for ; Mon, 1 Apr 2019 17:19:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554139159; bh=qiMdIuAX3nUN7iUbKCYtoZAHtGw2AkMeIy9DCjLm8RQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Q5ObloQ6VZP1DUIDE7CVmIvUaQu/ZL7udcveni3lw6CI2rFE2cMcOmS+DqQYJ3z2z 730wNbmyyW1qd/LVzGUzyLbuy+zWpkBIQzl4A9OP0pHaPlXR1e11ck7Ia69q2a2+xf 1eytcCiHrYQ4Bgty1jMoP0FvHfI2aINisKCTTNOg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731493AbfDARTS (ORCPT ); Mon, 1 Apr 2019 13:19:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:46862 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731475AbfDARTJ (ORCPT ); Mon, 1 Apr 2019 13:19:09 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 13ADC206C0; Mon, 1 Apr 2019 17:19:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554139147; bh=qiMdIuAX3nUN7iUbKCYtoZAHtGw2AkMeIy9DCjLm8RQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LHVK7I8NaTPpsLdn7G7OpjLE91CMCkCP/dQUrmmw/l+sK9uVX1vlujQ81QMeBjRBg DYiM3oANR6kfV5DrAFyQuSQ4HWS/g0Pm/qD8UmuKfofnYcsvN3tptnZB2+BxQd6Uh8 IUdSg6Z7e89FZWQmV/xMBMJTaTG0KZDjLwOGblD4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xu Yu , Daniel Borkmann Subject: [PATCH 4.19 128/134] bpf: do not restore dst_reg when cur_state is freed Date: Mon, 1 Apr 2019 19:02:44 +0200 Message-Id: <20190401170056.199327011@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190401170044.243719205@linuxfoundation.org> References: <20190401170044.243719205@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xu Yu commit 0803278b0b4d8eeb2b461fb698785df65a725d9e upstream. Syzkaller hit 'KASAN: use-after-free Write in sanitize_ptr_alu' bug. Call trace: dump_stack+0xbf/0x12e print_address_description+0x6a/0x280 kasan_report+0x237/0x360 sanitize_ptr_alu+0x85a/0x8d0 adjust_ptr_min_max_vals+0x8f2/0x1ca0 adjust_reg_min_max_vals+0x8ed/0x22e0 do_check+0x1ca6/0x5d00 bpf_check+0x9ca/0x2570 bpf_prog_load+0xc91/0x1030 __se_sys_bpf+0x61e/0x1f00 do_syscall_64+0xc8/0x550 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fault injection trace:  kfree+0xea/0x290  free_func_state+0x4a/0x60  free_verifier_state+0x61/0xe0  push_stack+0x216/0x2f0 <- inject failslab  sanitize_ptr_alu+0x2b1/0x8d0  adjust_ptr_min_max_vals+0x8f2/0x1ca0  adjust_reg_min_max_vals+0x8ed/0x22e0  do_check+0x1ca6/0x5d00  bpf_check+0x9ca/0x2570  bpf_prog_load+0xc91/0x1030  __se_sys_bpf+0x61e/0x1f00  do_syscall_64+0xc8/0x550  entry_SYSCALL_64_after_hwframe+0x49/0xbe When kzalloc() fails in push_stack(), free_verifier_state() will free current verifier state. As push_stack() returns, dst_reg was restored if ptr_is_dst_reg is false. However, as member of the cur_state, dst_reg is also freed, and error occurs when dereferencing dst_reg. Simply fix it by testing ret of push_stack() before restoring dst_reg. Fixes: 979d63d50c0c ("bpf: prevent out of bounds speculation on pointer arithmetic") Signed-off-by: Xu Yu Signed-off-by: Daniel Borkmann Signed-off-by: Greg Kroah-Hartman --- kernel/bpf/verifier.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2815,7 +2815,7 @@ do_sim: *dst_reg = *ptr_reg; } ret = push_stack(env, env->insn_idx + 1, env->insn_idx, true); - if (!ptr_is_dst_reg) + if (!ptr_is_dst_reg && ret) *dst_reg = tmp; return !ret ? -EFAULT : 0; }