From patchwork Fri May 1 13:23:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 226593 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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, 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 48EA1C47253 for ; Fri, 1 May 2020 13:47:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2970C2051A for ; Fri, 1 May 2020 13:47:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588340840; bh=kiWs6g3/hgzrVVzTYEvidsYjSeFIEvut602eFJMuhpU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JqCQ7eE82538cjRXX1w+0JEk5lwybNzOy9Sdi35nFntZLUbPhJgZ7cxsE54JPs20r t8lENX8trh7AG763ahDD4FkFKieUTwm9SSJUGoykJpK27KgDVjvSz0y5LH087hyu9T KIskCuJTHSJ0+COaNUuX9HHxDuPf2rv/EWURg9Pw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731360AbgEANrQ (ORCPT ); Fri, 1 May 2020 09:47:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:44940 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731683AbgEANnz (ORCPT ); Fri, 1 May 2020 09:43:55 -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 770AE208C3; Fri, 1 May 2020 13:43:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1588340634; bh=kiWs6g3/hgzrVVzTYEvidsYjSeFIEvut602eFJMuhpU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GGVr4VHiH8VtOvKAOakaa4wLJhOPJKHZu7I4V0SWF394myru+pEYWCaPiIE7xJc07 SO9m/Bqxi96y+t8lnzrQvk75xq4rwuf7yd22G0OB1bw72pxBoAGNl8DvPAL7PBEG5q cUWWHMwx9WWNjMgmcGPK3HHpH0txuKzh0w7hSOpc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Xi Wang , Luke Nelson , Alexei Starovoitov , Wang YanQing Subject: [PATCH 5.6 062/106] bpf, x86_32: Fix clobbering of dst for BPF_JSET Date: Fri, 1 May 2020 15:23:35 +0200 Message-Id: <20200501131551.017586610@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200501131543.421333643@linuxfoundation.org> References: <20200501131543.421333643@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Luke Nelson 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: Greg Kroah-Hartman --- arch/x86/net/bpf_jit_comp32.c | 22 ++++++++++++++++++---- 1 file changed, 18 insertions(+), 4 deletions(-) --- 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_p 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_p 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_p 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_p 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 */