From patchwork Tue Apr 21 17:15:51 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luke Nelson X-Patchwork-Id: 220825 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=-9.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 91E3BC54FC9 for ; Tue, 21 Apr 2020 17:16:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73062206F4 for ; Tue, 21 Apr 2020 17:16:26 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cs.washington.edu header.i=@cs.washington.edu header.b="LgOv8iFo" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729470AbgDURQZ (ORCPT ); Tue, 21 Apr 2020 13:16:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46228 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729373AbgDURQI (ORCPT ); Tue, 21 Apr 2020 13:16:08 -0400 Received: from mail-pl1-x641.google.com (mail-pl1-x641.google.com [IPv6:2607:f8b0:4864:20::641]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E2E59C0610D6 for ; Tue, 21 Apr 2020 10:16:07 -0700 (PDT) Received: by mail-pl1-x641.google.com with SMTP id g2so5481525plo.3 for ; Tue, 21 Apr 2020 10:16:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.washington.edu; s=goo201206; h=from:to:cc:subject:date:message-id; bh=ljRvWFcGm52XgUtMD9But5MqOn9lfvTXOY7h72QTuF4=; b=LgOv8iFo7ZZEXlbneCiwfho6goWloKWgxGo/Rz0rGHn1OF9OjCxjdtBD93lWXc2ryS oC+ZeG30GjIplDDTb5rlY3sS+29v6Xjreempc3mY7THUY0mn/sCkhG+akNtQspI4YGMi +eOjxBC8WDg43qS9kBWyj0nmuDk5bJie4voxo= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=ljRvWFcGm52XgUtMD9But5MqOn9lfvTXOY7h72QTuF4=; b=TIW3ZX2nlEe6TYkYwFcmO5PPSkeVuiMp/+5Knwe1nISqaQ37XGQtqqd2Ww3bwiVvNc ITT8eVb9lYhwvDw/iSHOweMN6lB3w9iC3XS6rtmUveHBxZw9OA0luC4NVZPq3EFVp96q LxDjy6e/y9k6EUmi3r+/ojcEoipjtOx94c5nPTemtTTV5OqOpBKY7NkpFOM89GtlPWVf d0v/hwlvY8NnQZTwxTh8U+05c6kABcwrnL47iMaShjbgqFRV/hIIlSiq2M0Zmm+yPAO8 3XApZc+q8bGIuVSER8JjEn/nu1VRes9TWSW6mpcyLbWQXggCDfSkAD/72fu/mFWfs1YR btjw== X-Gm-Message-State: AGi0PubEdqTr8RefBnQDfXsimKRcmD6xZVudn1ek3jLF2DwAsVx5F/1W K17HvVu+M8T89K14zWO5mliqgQ== X-Google-Smtp-Source: APiQypIiAshAlC23+kzaiUR/PvrllP1bebPd0TXXGjN+cCqgMI61CKL5fooN6QGFbYm7X73pWxgNnw== X-Received: by 2002:a17:90a:1946:: with SMTP id 6mr5214874pjh.42.1587489367134; Tue, 21 Apr 2020 10:16:07 -0700 (PDT) Received: from localhost.localdomain (c-73-53-94-119.hsd1.wa.comcast.net. [73.53.94.119]) by smtp.gmail.com with ESMTPSA id mn1sm2911459pjb.24.2020.04.21.10.16.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2020 10:16:06 -0700 (PDT) From: Luke Nelson X-Google-Original-From: Luke Nelson To: bpf@vger.kernel.org Cc: Luke Nelson , Xi Wang , Wang YanQing , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf 1/2] bpf, x32: Fix invalid instruction in BPF_LDX zero-extension Date: Tue, 21 Apr 2020 10:15:51 -0700 Message-Id: <20200421171552.28393-1-luke.r.nels@gmail.com> X-Mailer: git-send-email 2.17.1 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The current JIT uses the following sequence to zero-extend into the upper 32 bits of the destination register for BPF_LDX BPF_{B,H,W}, when the destination register is not on the stack: EMIT3(0xC7, add_1reg(0xC0, dst_hi), 0); However, this is not a valid instruction on x86. This patch fixes the problem by instead emitting "xor dst_hi,dst_hi" to clear the upper 32 bits. 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, and the verifier implements a zero-extension optimization. But the JIT should avoid emitting invalid instructions regardless. Fixes: 03f5781be2c7b ("bpf, x86_32: add eBPF JIT compiler for ia32") Signed-off-by: Xi Wang Signed-off-by: Luke Nelson --- arch/x86/net/bpf_jit_comp32.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/arch/x86/net/bpf_jit_comp32.c b/arch/x86/net/bpf_jit_comp32.c index 4d2a7a764602..cc9ad3892ea6 100644 --- a/arch/x86/net/bpf_jit_comp32.c +++ b/arch/x86/net/bpf_jit_comp32.c @@ -1854,7 +1854,9 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, STACK_VAR(dst_hi)); EMIT(0x0, 4); } else { - EMIT3(0xC7, add_1reg(0xC0, dst_hi), 0); + /* xor dst_hi,dst_hi */ + EMIT2(0x33, + add_2reg(0xC0, dst_hi, dst_hi)); } break; case BPF_DW: From patchwork Tue Apr 21 17:15:52 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luke Nelson X-Patchwork-Id: 220826 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=-9.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 63A34C54FCC for ; Tue, 21 Apr 2020 17:16:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 401242074B for ; Tue, 21 Apr 2020 17:16:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cs.washington.edu header.i=@cs.washington.edu header.b="FXIQhFby" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729436AbgDURQO (ORCPT ); Tue, 21 Apr 2020 13:16:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46236 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729403AbgDURQJ (ORCPT ); Tue, 21 Apr 2020 13:16:09 -0400 Received: from mail-pg1-x544.google.com (mail-pg1-x544.google.com [IPv6:2607:f8b0:4864:20::544]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 108DEC0610D5 for ; Tue, 21 Apr 2020 10:16:09 -0700 (PDT) Received: by mail-pg1-x544.google.com with SMTP id o185so6519888pgo.3 for ; Tue, 21 Apr 2020 10:16:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cs.washington.edu; s=goo201206; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=JLSvbU4rb+oShXf3/xaOIk/8iC3V7cv0pXPIaRB7gas=; b=FXIQhFbyFxDd0yfZDoveFyAYihbUpl0AsbLQrJYGlMwBXwAiFuFrmwg33A6vQn9BxY 0hEWwUtLK3H2dHb5eKlhTwcqQlbUJRC/m041/yaerXwlJ+oEz1DO1rViNnSaOP0nh/tm 3iYPRWmJY3YmVlhE1BeKRDTOjICFezTU+5Ld4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=JLSvbU4rb+oShXf3/xaOIk/8iC3V7cv0pXPIaRB7gas=; b=IhQ79N0UhWMMuAWD7YEeTL2AzNAk5361yuRgjknN1ffZnnU66QXYWBhc606vXBU61m 9S1ZOHvPyb5xQk7yebYz0n2SzjOhvihhhEc9+P+JQfUDfoqNWga4z6341JAMcXfrviNe lvUmifHtguj2jO44BQgdyqupvhr7x7ZXwBVqzZdxLWoxxMCFUVW/nj7titNCMU1Z4dp/ JeRbz2JjSuH5dBBfztWDDRU9DgIz97dcODthCF+0c9q1emw8bmPZMhsquG5kG2hQkyje r1t2YMPxVoYzuA6MBI26HEtftdUNu7MyiVOZRxRFUXDQdsdZYItFmBWhr3n6R2r97HXw 9BTQ== X-Gm-Message-State: AGi0PubYDdv3vvl1/DytuvBOKyEXwvFUF0XxeYmfxsmbL5Fjqf8efRcH +oAUqrr1CMVeyvFJpFtXltvmDQ== X-Google-Smtp-Source: APiQypJPoDAmSxZXe01yomlBdjPcOGDJGtKwAq2V7OtTrQuozGcBYLfIfUYNkfTKOSgfuq3DcKg29A== X-Received: by 2002:a63:b23:: with SMTP id 35mr10303567pgl.170.1587489368378; Tue, 21 Apr 2020 10:16:08 -0700 (PDT) Received: from localhost.localdomain (c-73-53-94-119.hsd1.wa.comcast.net. [73.53.94.119]) by smtp.gmail.com with ESMTPSA id mn1sm2911459pjb.24.2020.04.21.10.16.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 21 Apr 2020 10:16:07 -0700 (PDT) From: Luke Nelson X-Google-Original-From: Luke Nelson To: bpf@vger.kernel.org Cc: Luke Nelson , Xi Wang , "David S. Miller" , Alexey Kuznetsov , Hideaki YOSHIFUJI , Wang YanQing , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H. Peter Anvin" , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , Andrii Nakryiko , John Fastabend , KP Singh , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf 2/2] bpf, x32: Fix clobbering of dst for BPF_JSET Date: Tue, 21 Apr 2020 10:15:52 -0700 Message-Id: <20200421171552.28393-2-luke.r.nels@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200421171552.28393-1-luke.r.nels@gmail.com> References: <20200421171552.28393-1-luke.r.nels@gmail.com> Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 --- arch/x86/net/bpf_jit_comp32.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) diff --git a/arch/x86/net/bpf_jit_comp32.c b/arch/x86/net/bpf_jit_comp32.c index cc9ad3892ea6..ba7d9ccfc662 100644 --- a/arch/x86/net/bpf_jit_comp32.c +++ b/arch/x86/net/bpf_jit_comp32.c @@ -2015,8 +2015,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, case BPF_JMP | BPF_JSET | BPF_X: case BPF_JMP32 | BPF_JSET | BPF_X: { bool is_jmp64 = BPF_CLASS(insn->code) == BPF_JMP; - 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; @@ -2028,6 +2028,13 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 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)); + if (is_jmp64) + /* mov dreg_hi,dst_hi */ + EMIT2(0x89, + add_2reg(0xC0, dreg_hi, dst_hi)); } if (sstk) { @@ -2052,8 +2059,8 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, case BPF_JMP | BPF_JSET | BPF_K: case BPF_JMP32 | BPF_JSET | BPF_K: { bool is_jmp64 = BPF_CLASS(insn->code) == BPF_JMP; - 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; u32 hi; @@ -2066,6 +2073,13 @@ static int do_jit(struct bpf_prog *bpf_prog, int *addrs, u8 *image, 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)); + if (is_jmp64) + /* mov dreg_hi,dst_hi */ + EMIT2(0x89, + add_2reg(0xC0, dreg_hi, dst_hi)); } /* mov ecx,imm32 */