From patchwork Tue May 26 18:53:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 225362 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, 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 3EE48C433E1 for ; Tue, 26 May 2020 19:08:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B501208B3 for ; Tue, 26 May 2020 19:08:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520121; bh=+CcGc1ePsAEy4vbCoNwEklXLyLYAmR7rlXdXCWM57Is=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MI9e5Og6xytRco/9PkAyG2dO4A8w6fiYvOMP6PHWHRfXLWi9zt5Gd4xtivsDdi/3w L2maHJjg1RsfQn+wpp1cZzVOd4lzVVHaXbT8NKedAqcZ8yb7lH29F7HruSqrEvY9Ul n3z3hq9OSHJsLSwzgjsSUM0XFueCkEEKJ+H7rfn4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2403906AbgEZTIj (ORCPT ); Tue, 26 May 2020 15:08:39 -0400 Received: from mail.kernel.org ([198.145.29.99]:37640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403842AbgEZTIh (ORCPT ); Tue, 26 May 2020 15:08:37 -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 08BB0208C3; Tue, 26 May 2020 19:08:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590520117; bh=+CcGc1ePsAEy4vbCoNwEklXLyLYAmR7rlXdXCWM57Is=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SRIer6hdk5fTHXUiQnGtU/giZX3vndG7PfyafZ/vrPwmoma/HGtr2JtNQs4ei+ucV HxJOyDGb54A4ILghJ3phSXdEyXBe5biok9L3tq3wiyGR87IJDtIgxCBbly/UYNtC5D lfjljxySYrnW9fTawrgJyhyPLhCfTLD/CbfU4Jok= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Keno Fischer , Will Deacon , Sudeep Holla , Bin Lu , Catalin Marinas Subject: [PATCH 5.4 064/111] arm64: Fix PTRACE_SYSEMU semantics Date: Tue, 26 May 2020 20:53:22 +0200 Message-Id: <20200526183938.924435089@linuxfoundation.org> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20200526183932.245016380@linuxfoundation.org> References: <20200526183932.245016380@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: Keno Fischer commit 1cf6022bd9161081215028203919c33fcfa6debb upstream. Quoth the man page: ``` If the tracee was restarted by PTRACE_SYSCALL or PTRACE_SYSEMU, the tracee enters syscall-enter-stop just prior to entering any system call (which will not be executed if the restart was using PTRACE_SYSEMU, regardless of any change made to registers at this point or how the tracee is restarted after this stop). ``` The parenthetical comment is currently true on x86 and powerpc, but not currently true on arm64. arm64 re-checks the _TIF_SYSCALL_EMU flag after the syscall entry ptrace stop. However, at this point, it reflects which method was used to re-start the syscall at the entry stop, rather than the method that was used to reach it. Fix that by recording the original flag before performing the ptrace stop, bringing the behavior in line with documentation and x86/powerpc. Fixes: f086f67485c5 ("arm64: ptrace: add support for syscall emulation") Cc: # 5.3.x- Signed-off-by: Keno Fischer Acked-by: Will Deacon Tested-by: Sudeep Holla Tested-by: Bin Lu [catalin.marinas@arm.com: moved 'flags' bit masking] [catalin.marinas@arm.com: changed 'flags' type to unsigned long] Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/kernel/ptrace.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -1829,10 +1829,11 @@ static void tracehook_report_syscall(str int syscall_trace_enter(struct pt_regs *regs) { - if (test_thread_flag(TIF_SYSCALL_TRACE) || - test_thread_flag(TIF_SYSCALL_EMU)) { + unsigned long flags = READ_ONCE(current_thread_info()->flags); + + if (flags & (_TIF_SYSCALL_EMU | _TIF_SYSCALL_TRACE)) { tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER); - if (!in_syscall(regs) || test_thread_flag(TIF_SYSCALL_EMU)) + if (!in_syscall(regs) || (flags & _TIF_SYSCALL_EMU)) return -1; }