From patchwork Mon Feb 5 18:23:03 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 10201135 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 2FDDA601A1 for ; Mon, 5 Feb 2018 18:27:20 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2098C287A4 for ; Mon, 5 Feb 2018 18:27:20 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 147A1287AA; Mon, 5 Feb 2018 18:27:20 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.2 required=2.0 tests=BAYES_00, RCVD_IN_DNSWL_MED autolearn=ham version=3.3.1 Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.wl.linuxfoundation.org (Postfix) with SMTP id D0D22287A4 for ; Mon, 5 Feb 2018 18:27:17 +0000 (UTC) Received: (qmail 19787 invoked by uid 550); 5 Feb 2018 18:25:10 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 19499 invoked from network); 5 Feb 2018 18:25:02 -0000 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Dan Williams , Thomas Gleixner , linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, Andy Lutomirski , alan@linux.intel.com Subject: [PATCH 4.14 44/64] x86/syscall: Sanitize syscall table de-references under speculation Date: Mon, 5 Feb 2018 10:23:03 -0800 Message-Id: <20180205182140.385565178@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180205182138.571333346@linuxfoundation.org> References: <20180205182138.571333346@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 X-Virus-Scanned: ClamAV using ClamSMTP 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams dan.j.williams@intel.com commit 2fbd7af5af8665d18bcefae3e9700be07e22b681 The syscall table base is a user controlled function pointer in kernel space. Use array_index_nospec() to prevent any out of bounds speculation. While retpoline prevents speculating into a userspace directed target it does not stop the pointer de-reference, the concern is leaking memory relative to the syscall table base, by observing instruction cache behavior. Reported-by: Linus Torvalds Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Andy Lutomirski Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727417984.33451.1216731042505722161.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/common.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -284,7 +285,8 @@ __visible void do_syscall_64(struct pt_r * regs->orig_ax, which changes the behavior of some syscalls. */ if (likely((nr & __SYSCALL_MASK) < NR_syscalls)) { - regs->ax = sys_call_table[nr & __SYSCALL_MASK]( + nr = array_index_nospec(nr & __SYSCALL_MASK, NR_syscalls); + regs->ax = sys_call_table[nr]( regs->di, regs->si, regs->dx, regs->r10, regs->r8, regs->r9); } @@ -320,6 +322,7 @@ static __always_inline void do_syscall_3 } if (likely(nr < IA32_NR_syscalls)) { + nr = array_index_nospec(nr, IA32_NR_syscalls); /* * It's possible that a 32-bit syscall implementation * takes a 64-bit parameter but nonetheless assumes that