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=-6.1 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=ham 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 86E76C10F14 for ; Thu, 18 Apr 2019 18:23:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 581702064A for ; Thu, 18 Apr 2019 18:23:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555611801; bh=5L7MLfi6prf6oZEelu7lYa931f5zPNtr7ggsATV8zw8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=teVQaGeCUJExXstvmpSJrg4MHFxiga8BkiwpDozMpXHsQpzhF7XKUrbOqdKGpJMDt ImfPBG7hSMX7bZqJXPiZz3k3fQdjXDwvkDh3SBac4zTfr9MgSOdFs8QkkaHPYHJgkb rht9GLJwNTX6FZBJe8Ffcw5BzgyBlGkg2SNPi91c= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404093AbfDRSXU (ORCPT ); Thu, 18 Apr 2019 14:23:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:36460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390479AbfDRSGf (ORCPT ); Thu, 18 Apr 2019 14:06:35 -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 566722186A; Thu, 18 Apr 2019 18:06:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555610794; bh=5L7MLfi6prf6oZEelu7lYa931f5zPNtr7ggsATV8zw8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XhUXZMae8P/F8T+NU0vVLnFMQ58xbWzC12puFhBIpFzYMkJzIlXFKdU8xolgaoa2e smKWIfY2WxHQG0fOa0PJaH/ZlfhCj/hBgeQcKbRr/wGp3gfgxbmd87YiUhbfPjBzdm XeuEgj3JK/cjcS6ktQa1GjqV8rDcJnyj8atfiaJM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xu Yu , Daniel Borkmann Subject: [PATCH 4.14 87/92] bpf: do not restore dst_reg when cur_state is freed Date: Thu, 18 Apr 2019 19:57:45 +0200 Message-Id: <20190418160438.102407405@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190418160430.325165109@linuxfoundation.org> References: <20190418160430.325165109@linuxfoundation.org> User-Agent: quilt/0.66 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 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 @@ -2118,7 +2118,7 @@ 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; }