From patchwork Mon Mar 29 07:58:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 411609 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, 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 91796C433E2 for ; Mon, 29 Mar 2021 08:06:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6DFEB6196B for ; Mon, 29 Mar 2021 08:06:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231728AbhC2IFi (ORCPT ); Mon, 29 Mar 2021 04:05:38 -0400 Received: from mail.kernel.org ([198.145.29.99]:47402 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231904AbhC2IEt (ORCPT ); Mon, 29 Mar 2021 04:04:49 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 103D461938; Mon, 29 Mar 2021 08:04:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1617005088; bh=Iq5FXPDhFOfOwScZYi6m5AIIwfnC4IBfoCPjd3956Ms=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sqF6sn9iMFedm2o0JM28PzEMcK56jcUx+oGE27KdPcyYlVFyKryf4Ujfs8NzpVuWQ tisDX0QXyoxOj9pTFUMmkMnzZpRNQstbqJEOzvPBBZaIOzSRI1Ys1NpEXLbELt/k/+ TPT4tbzUSVqsxf5ZUc6t5absoRFGyfyzquO+3IaA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sergei Trofimovich , "Dmitry V. Levin" , Oleg Nesterov , John Paul Adrian Glaubitz , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.14 20/59] ia64: fix ia64_syscall_get_set_arguments() for break-based syscalls Date: Mon, 29 Mar 2021 09:58:00 +0200 Message-Id: <20210329075609.552547217@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210329075608.898173317@linuxfoundation.org> References: <20210329075608.898173317@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sergei Trofimovich [ Upstream commit 0ceb1ace4a2778e34a5414e5349712ae4dc41d85 ] In https://bugs.gentoo.org/769614 Dmitry noticed that `ptrace(PTRACE_GET_SYSCALL_INFO)` does not work for syscalls called via glibc's syscall() wrapper. ia64 has two ways to call syscalls from userspace: via `break` and via `eps` instructions. The difference is in stack layout: 1. `eps` creates simple stack frame: no locals, in{0..7} == out{0..8} 2. `break` uses userspace stack frame: may be locals (glibc provides one), in{0..7} == out{0..8}. Both work fine in syscall handling cde itself. But `ptrace(PTRACE_GET_SYSCALL_INFO)` uses unwind mechanism to re-extract syscall arguments but it does not account for locals. The change always skips locals registers. It should not change `eps` path as kernel's handler already enforces locals=0 and fixes `break`. Tested on v5.10 on rx3600 machine (ia64 9040 CPU). Link: https://lkml.kernel.org/r/20210221002554.333076-1-slyfox@gentoo.org Link: https://bugs.gentoo.org/769614 Signed-off-by: Sergei Trofimovich Reported-by: Dmitry V. Levin Cc: Oleg Nesterov Cc: John Paul Adrian Glaubitz Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- arch/ia64/kernel/ptrace.c | 24 ++++++++++++++++++------ 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/arch/ia64/kernel/ptrace.c b/arch/ia64/kernel/ptrace.c index 427cd565fd61..799400287cda 100644 --- a/arch/ia64/kernel/ptrace.c +++ b/arch/ia64/kernel/ptrace.c @@ -2147,27 +2147,39 @@ static void syscall_get_set_args_cb(struct unw_frame_info *info, void *data) { struct syscall_get_set_args *args = data; struct pt_regs *pt = args->regs; - unsigned long *krbs, cfm, ndirty; + unsigned long *krbs, cfm, ndirty, nlocals, nouts; int i, count; if (unw_unwind_to_user(info) < 0) return; + /* + * We get here via a few paths: + * - break instruction: cfm is shared with caller. + * syscall args are in out= regs, locals are non-empty. + * - epsinstruction: cfm is set by br.call + * locals don't exist. + * + * For both cases argguments are reachable in cfm.sof - cfm.sol. + * CFM: [ ... | sor: 17..14 | sol : 13..7 | sof : 6..0 ] + */ cfm = pt->cr_ifs; + nlocals = (cfm >> 7) & 0x7f; /* aka sol */ + nouts = (cfm & 0x7f) - nlocals; /* aka sof - sol */ krbs = (unsigned long *)info->task + IA64_RBS_OFFSET/8; ndirty = ia64_rse_num_regs(krbs, krbs + (pt->loadrs >> 19)); count = 0; if (in_syscall(pt)) - count = min_t(int, args->n, cfm & 0x7f); + count = min_t(int, args->n, nouts); + /* Iterate over outs. */ for (i = 0; i < count; i++) { + int j = ndirty + nlocals + i + args->i; if (args->rw) - *ia64_rse_skip_regs(krbs, ndirty + i + args->i) = - args->args[i]; + *ia64_rse_skip_regs(krbs, j) = args->args[i]; else - args->args[i] = *ia64_rse_skip_regs(krbs, - ndirty + i + args->i); + args->args[i] = *ia64_rse_skip_regs(krbs, j); } if (!args->rw) {