From patchwork Fri May 1 03:19:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wang YanQing X-Patchwork-Id: 226711 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=-8.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 BA986C47256 for ; Fri, 1 May 2020 03:21:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9AD2520857 for ; Fri, 1 May 2020 03:21:03 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TF5Vs1fw" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728008AbgEADVD (ORCPT ); Thu, 30 Apr 2020 23:21:03 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727889AbgEADVC (ORCPT ); Thu, 30 Apr 2020 23:21:02 -0400 Received: from mail-pf1-x444.google.com (mail-pf1-x444.google.com [IPv6:2607:f8b0:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 891E5C035494; Thu, 30 Apr 2020 20:21:02 -0700 (PDT) Received: by mail-pf1-x444.google.com with SMTP id w65so1027791pfc.12; Thu, 30 Apr 2020 20:21:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition :user-agent; bh=7HcFBMjFrcWXcaxPCvfiay+8yWpZ9NZg39Yk9Jl8op0=; b=TF5Vs1fwPQOCnlfaNvn4W0v54ALE0gsIf2jWbByFcOhcRjcv+8g9PdxdnaQiJD3cGn L9/EaHQ3l0ZDngMKA1wKsT6r7oY9BL9D5Kejf1gAOEmLTIUEU/SVD2aVAtwXomEARLLU jVEiKYe0ZF573PUViQST43ljHjC6z0OUIX7g4rDgvJMgERV2L+UAkOeZLO3FJNqFXdAs CMJiuJNBUzNym93HNWg4GKoiQKBvKKOAUVO1dTSl5FpNd+RfeISYQjRUVkLV3iIg5C9X hZ9Yq3e56k4IAEd6TLcvTlaNsOruaWrcDkC6xoSYcbTB745Gso5XQCLlJI1LONT6fOLZ HTUg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition:user-agent; bh=7HcFBMjFrcWXcaxPCvfiay+8yWpZ9NZg39Yk9Jl8op0=; b=svq9U+ERQJOUzgzyTz/NOR5A+mYbDtQcrW7W8ETGX0OGkGBPb4xZv+0cMG3jzqG8Mw kKbMscJD0lrYfrj8KaBcZjgIqGB+6ubMDf/nfqfdfvJ22zVWUhWo2Vt77Rszc8j6Qxr/ XxwyeyDy57hsz7uTyCO3OHNlxSek+U6DRJc/Q65O8fcHMs6oK3yekodwV6X86XPsSCxz stjfVOuoKfRxovI8Q/K97mMXLgjJomrcwgc3OLyXPb+h+17zTMy//8Qi5EapoBZ0Ww2A TPaDRzew6qMMklnaiBTgMO3qaOXVz5o6jBHvOCICvCQZLzPRvJwEw2J6SG72M6sGl0Jo emIw== X-Gm-Message-State: AGi0PuZnMKD6UpgVhvQ8MRkXS//s7eTgpo/0zxweygYJFuErCgYSWvNw pH42LmXZj3qEZFm/Yw3NSg2LA9qM X-Google-Smtp-Source: APiQypLfb1YXmzbFRiuEgKV/Fek4g9O8acitGrv3m5ooOwF6yHNTgnBCT+REDBRFFZew8D4hpKxPYA== X-Received: by 2002:a63:e503:: with SMTP id r3mr2339270pgh.106.1588303261729; Thu, 30 Apr 2020 20:21:01 -0700 (PDT) Received: from udknight.localhost ([59.57.158.27]) by smtp.gmail.com with ESMTPSA id s199sm994550pfs.124.2020.04.30.20.21.00 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 30 Apr 2020 20:21:00 -0700 (PDT) Received: from udknight.localhost (localhost [127.0.0.1]) by udknight.localhost (8.14.9/8.14.4) with ESMTP id 0413Jq3P004819; Fri, 1 May 2020 11:19:52 +0800 Received: (from root@localhost) by udknight.localhost (8.14.9/8.14.9/Submit) id 0413JorC004818; Fri, 1 May 2020 11:19:50 +0800 Date: Fri, 1 May 2020 11:19:50 +0800 From: Wang YanQing To: stable@vger.kernel.org Cc: gregkh@linuxfoundation.org, lukenels@cs.washington.edu, ast@kernel.org, luke.r.nels@gmail.com, udknight@gmail.com, xi.wang@gmail.com, daniel@iogearbox.net, bpf@vger.kernel.org Subject: [PATCH] bpf, x86_32: Fix clobbering of dst for BPF_JSET Message-ID: <20200501031950.GA4782@udknight> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.7.1 (2016-10-04) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org commit 50fe7ebb6475711c15b3397467e6424e20026d94 upstream. The current JIT clobbers the destination register for BPF_JSET BPF_X and BPF_K by using "and" and "or" instructions. This is fine when the destination register is a temporary loaded from a register stored on the stack but not otherwise. This patch fixes the problem (for both BPF_K and BPF_X) by always loading the destination register into temporaries since BPF_JSET should not modify the destination register. This bug may not be currently triggerable as BPF_REG_AX is the only register not stored on the stack and the verifier uses it in a limited way. Fixes: 03f5781be2c7b ("bpf, x86_32: add eBPF JIT compiler for ia32") Signed-off-by: Xi Wang Signed-off-by: Luke Nelson Signed-off-by: Alexei Starovoitov Acked-by: Wang YanQing Link: https://lore.kernel.org/bpf/20200422173630.8351-2-luke.r.nels@gmail.com Signed-off-by: Wang YanQing --- arch/x86/net/bpf_jit_comp32.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp32.c b/arch/x86/net/bpf_jit_comp32.c index 24d573b..7e7ca5d 100644 --- a/arch/x86/net/bpf_jit_comp32.c +++ b/arch/x86/net/bpf_jit_comp32.c @@ -1968,8 +1968,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, goto emit_cond_jmp_signed; } case BPF_JMP | BPF_JSET | BPF_X: { - u8 dreg_lo = dstk ? IA32_EAX : dst_lo; - u8 dreg_hi = dstk ? IA32_EDX : dst_hi; + u8 dreg_lo = IA32_EAX; + u8 dreg_hi = IA32_EDX; u8 sreg_lo = sstk ? IA32_ECX : src_lo; u8 sreg_hi = sstk ? IA32_EBX : src_hi; @@ -1978,6 +1978,12 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, STACK_VAR(dst_lo)); EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(dst_hi)); + } else { + /* mov dreg_lo,dst_lo */ + EMIT2(0x89, add_2reg(0xC0, dreg_lo, dst_lo)); + /* mov dreg_hi,dst_hi */ + EMIT2(0x89, + add_2reg(0xC0, dreg_hi, dst_hi)); } if (sstk) { @@ -1996,8 +2002,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, } case BPF_JMP | BPF_JSET | BPF_K: { u32 hi; - u8 dreg_lo = dstk ? IA32_EAX : dst_lo; - u8 dreg_hi = dstk ? IA32_EDX : dst_hi; + u8 dreg_lo = IA32_EAX; + u8 dreg_hi = IA32_EDX; u8 sreg_lo = IA32_ECX; u8 sreg_hi = IA32_EBX; @@ -2006,6 +2012,12 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, STACK_VAR(dst_lo)); EMIT3(0x8B, add_2reg(0x40, IA32_EBP, IA32_EDX), STACK_VAR(dst_hi)); + } else { + /* mov dreg_lo,dst_lo */ + EMIT2(0x89, add_2reg(0xC0, dreg_lo, dst_lo)); + /* mov dreg_hi,dst_hi */ + EMIT2(0x89, + add_2reg(0xC0, dreg_hi, dst_hi)); } hi = imm32 & (1<<31) ? (u32)~0 : 0;