From mboxrd@z Thu Jan 1 00:00:00 1970 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=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 CE647C433FE for ; Thu, 10 Dec 2020 19:37:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 81B1323340 for ; Thu, 10 Dec 2020 19:37:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2393461AbgLJThI (ORCPT ); Thu, 10 Dec 2020 14:37:08 -0500 Received: from mail.kernel.org ([198.145.29.99]:37172 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390182AbgLJO2z (ORCPT ); Thu, 10 Dec 2020 09:28:55 -0500 From: Greg Kroah-Hartman Authentication-Results: mail.kernel.org; dkim=permerror (bad message/signature format) To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com, Masami Hiramatsu , Borislav Petkov , Srikar Dronamraju , Sudip Mukherjee Subject: [PATCH 4.4 39/39] x86/uprobes: Do not use prefixes.nbytes when looping over prefixes.bytes Date: Thu, 10 Dec 2020 15:26:50 +0100 Message-Id: <20201210142602.805518260@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201210142600.887734129@linuxfoundation.org> References: <20201210142600.887734129@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Masami Hiramatsu commit 4e9a5ae8df5b3365183150f6df49e49dece80d8c upstream Since insn.prefixes.nbytes can be bigger than the size of insn.prefixes.bytes[] when a prefix is repeated, the proper check must be insn.prefixes.bytes[i] != 0 and i < 4 instead of using insn.prefixes.nbytes. Introduce a for_each_insn_prefix() macro for this purpose. Debugged by Kees Cook . [ bp: Massage commit message, sync with the respective header in tools/ and drop "we". ] Fixes: 2b1444983508 ("uprobes, mm, x86: Add the ability to install and remove uprobes breakpoints") Reported-by: syzbot+9b64b619f10f19d19a7c@syzkaller.appspotmail.com Signed-off-by: Masami Hiramatsu Signed-off-by: Borislav Petkov Reviewed-by: Srikar Dronamraju Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/160697103739.3146288.7437620795200799020.stgit@devnote2 [sudip: adjust context, drop change of insn.h in tools] Signed-off-by: Sudip Mukherjee Signed-off-by: Greg Kroah-Hartman --- arch/x86/include/asm/insn.h | 15 +++++++++++++++ arch/x86/kernel/uprobes.c | 10 ++++++---- 2 files changed, 21 insertions(+), 4 deletions(-) --- a/arch/x86/include/asm/insn.h +++ b/arch/x86/include/asm/insn.h @@ -198,6 +198,21 @@ static inline int insn_offset_immediate( return insn_offset_displacement(insn) + insn->displacement.nbytes; } +/** + * for_each_insn_prefix() -- Iterate prefixes in the instruction + * @insn: Pointer to struct insn. + * @idx: Index storage. + * @prefix: Prefix byte. + * + * Iterate prefix bytes of given @insn. Each prefix byte is stored in @prefix + * and the index is stored in @idx (note that this @idx is just for a cursor, + * do not change it.) + * Since prefixes.nbytes can be bigger than 4 if some prefixes + * are repeated, it cannot be used for looping over the prefixes. + */ +#define for_each_insn_prefix(insn, idx, prefix) \ + for (idx = 0; idx < ARRAY_SIZE(insn->prefixes.bytes) && (prefix = insn->prefixes.bytes[idx]) != 0; idx++) + #define POP_SS_OPCODE 0x1f #define MOV_SREG_OPCODE 0x8e --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -268,10 +268,11 @@ static volatile u32 good_2byte_insns[256 static bool is_prefix_bad(struct insn *insn) { + insn_byte_t p; int i; - for (i = 0; i < insn->prefixes.nbytes; i++) { - switch (insn->prefixes.bytes[i]) { + for_each_insn_prefix(insn, i, p) { + switch (p) { case 0x26: /* INAT_PFX_ES */ case 0x2E: /* INAT_PFX_CS */ case 0x36: /* INAT_PFX_DS */ @@ -711,6 +712,7 @@ static struct uprobe_xol_ops branch_xol_ static int branch_setup_xol_ops(struct arch_uprobe *auprobe, struct insn *insn) { u8 opc1 = OPCODE1(insn); + insn_byte_t p; int i; switch (opc1) { @@ -741,8 +743,8 @@ static int branch_setup_xol_ops(struct a * Intel and AMD behavior differ in 64-bit mode: Intel ignores 66 prefix. * No one uses these insns, reject any branch insns with such prefix. */ - for (i = 0; i < insn->prefixes.nbytes; i++) { - if (insn->prefixes.bytes[i] == 0x66) + for_each_insn_prefix(insn, i, p) { + if (p == 0x66) return -ENOTSUPP; }