From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226CnBpYsQ/3jrajAxr8l8Deji+Kq8zd2tk2KTklNjQX4mhHsfhhgVDuWyVzER6uzSwt2Obf ARC-Seal: i=1; a=rsa-sha256; t=1519217861; cv=none; d=google.com; s=arc-20160816; b=VuJSozgzGgn86/tubxLow2nHsLtpl91a/4ImEz5rtKkLZ6YUA226hXNiJrOUlJ2rhe yhYLR6TT4HOATMEM97+w8Ky95Q9L4cpqP3ORavq1VpD7oNee9wt11XDpdAzeYk0vhlU/ 23nC7fWI0XBB8BkYEZBvJ/+vHBJZwAFYBGPhTVyenMOX8/oYmdDZkp2QacYNd5JTBX0L 96iG/oZnO18PSHvZV6nrEBS006ReRiD027tI3GPzIttNy5Nts+4tNICKj7Blo/Q+PFug r1GL/aJPwulELAMpFek+ZpDUzXNorcWWampL1sWLlPTOg1j4ScCOwwJQ97EHo4zOda5C pwAw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=zxrfJOUf2Y6Y7cm2maE/u3CLEJDwkz+EtjFTD5AT4Og=; b=NGzJBaqG7ACq/qzitMP48hbOcLqIY7mPq4Hivmm3r3fq5CPG2nmCadxaNyENLacRLV j9GLA0kVQx1gWupAS+1mF7D7VXPZkQi3KFDBzcjkV5JVYIxnpapn+M5J1UZmFDcJTtli OKfey+GLOLIA7MSGoTLWSd8aLOuDCL00yhl4ncxQ2c/ffUoAJyOgA65Z1QpP8ThTKBGS ONE9Vh+yL0crp0xj1/q5ewxWH6UqcdQZBUulX8IE5tr3d+JnO47v7AbZjaGgMeFlg+iH H+fOXFhLGxQqBjb17k8suxM09lnyvr8vvz6G86UNhtUmjCuaDbe2dXFXiHG3FdEigRXP BI+A== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Williams , Andy Lutomirski , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.9 50/77] x86/entry/64/compat: Clear registers for compat syscalls, to reduce speculation attack surface Date: Wed, 21 Feb 2018 13:48:59 +0100 Message-Id: <20180221124434.315881447@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124432.172390020@linuxfoundation.org> References: <20180221124432.172390020@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593015388581637403?= X-GMAIL-MSGID: =?utf-8?q?1593015388581637403?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit 6b8cf5cc9965673951f1ab3f0e3cf23d06e3e2ee upstream. At entry userspace may have populated registers with values that could otherwise be useful in a speculative execution attack. Clear them to minimize the kernel's attack surface. Originally-From: Andi Kleen Signed-off-by: Dan Williams Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/151787989697.7847.4083702787288600552.stgit@dwillia2-desk3.amr.corp.intel.com [ Made small improvements to the changelog. ] Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/entry_64_compat.S | 30 ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+) --- a/arch/x86/entry/entry_64_compat.S +++ b/arch/x86/entry/entry_64_compat.S @@ -83,15 +83,25 @@ ENTRY(entry_SYSENTER_compat) pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */ pushq $0 /* pt_regs->r8 = 0 */ + xorq %r8, %r8 /* nospec r8 */ pushq $0 /* pt_regs->r9 = 0 */ + xorq %r9, %r9 /* nospec r9 */ pushq $0 /* pt_regs->r10 = 0 */ + xorq %r10, %r10 /* nospec r10 */ pushq $0 /* pt_regs->r11 = 0 */ + xorq %r11, %r11 /* nospec r11 */ pushq %rbx /* pt_regs->rbx */ + xorl %ebx, %ebx /* nospec rbx */ pushq %rbp /* pt_regs->rbp (will be overwritten) */ + xorl %ebp, %ebp /* nospec rbp */ pushq $0 /* pt_regs->r12 = 0 */ + xorq %r12, %r12 /* nospec r12 */ pushq $0 /* pt_regs->r13 = 0 */ + xorq %r13, %r13 /* nospec r13 */ pushq $0 /* pt_regs->r14 = 0 */ + xorq %r14, %r14 /* nospec r14 */ pushq $0 /* pt_regs->r15 = 0 */ + xorq %r15, %r15 /* nospec r15 */ cld /* @@ -209,15 +219,25 @@ ENTRY(entry_SYSCALL_compat) pushq %rbp /* pt_regs->cx (stashed in bp) */ pushq $-ENOSYS /* pt_regs->ax */ pushq $0 /* pt_regs->r8 = 0 */ + xorq %r8, %r8 /* nospec r8 */ pushq $0 /* pt_regs->r9 = 0 */ + xorq %r9, %r9 /* nospec r9 */ pushq $0 /* pt_regs->r10 = 0 */ + xorq %r10, %r10 /* nospec r10 */ pushq $0 /* pt_regs->r11 = 0 */ + xorq %r11, %r11 /* nospec r11 */ pushq %rbx /* pt_regs->rbx */ + xorl %ebx, %ebx /* nospec rbx */ pushq %rbp /* pt_regs->rbp (will be overwritten) */ + xorl %ebp, %ebp /* nospec rbp */ pushq $0 /* pt_regs->r12 = 0 */ + xorq %r12, %r12 /* nospec r12 */ pushq $0 /* pt_regs->r13 = 0 */ + xorq %r13, %r13 /* nospec r13 */ pushq $0 /* pt_regs->r14 = 0 */ + xorq %r14, %r14 /* nospec r14 */ pushq $0 /* pt_regs->r15 = 0 */ + xorq %r15, %r15 /* nospec r15 */ /* * User mode is traced as though IRQs are on, and SYSENTER @@ -320,15 +340,25 @@ ENTRY(entry_INT80_compat) pushq %rcx /* pt_regs->cx */ pushq $-ENOSYS /* pt_regs->ax */ pushq $0 /* pt_regs->r8 = 0 */ + xorq %r8, %r8 /* nospec r8 */ pushq $0 /* pt_regs->r9 = 0 */ + xorq %r9, %r9 /* nospec r9 */ pushq $0 /* pt_regs->r10 = 0 */ + xorq %r10, %r10 /* nospec r10 */ pushq $0 /* pt_regs->r11 = 0 */ + xorq %r11, %r11 /* nospec r11 */ pushq %rbx /* pt_regs->rbx */ + xorl %ebx, %ebx /* nospec rbx */ pushq %rbp /* pt_regs->rbp */ + xorl %ebp, %ebp /* nospec rbp */ pushq %r12 /* pt_regs->r12 */ + xorq %r12, %r12 /* nospec r12 */ pushq %r13 /* pt_regs->r13 */ + xorq %r13, %r13 /* nospec r13 */ pushq %r14 /* pt_regs->r14 */ + xorq %r14, %r14 /* nospec r14 */ pushq %r15 /* pt_regs->r15 */ + xorq %r15, %r15 /* nospec r15 */ cld /*