From patchwork Mon Apr 15 18:59:18 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 162251 Delivered-To: patch@linaro.org Received: by 2002:a02:c6d8:0:0:0:0:0 with SMTP id r24csp3297229jan; Mon, 15 Apr 2019 12:08:55 -0700 (PDT) X-Google-Smtp-Source: APXvYqxtUirRKdL37vCsaTsE2Zpr9loBHlvcbPO4al9j4I56gm+xTyBYqqPH1jPE4VzY5G4O2HWL X-Received: by 2002:a17:902:9a83:: with SMTP id w3mr78294758plp.241.1555355335672; Mon, 15 Apr 2019 12:08:55 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1555355335; cv=none; d=google.com; s=arc-20160816; b=SUll3Z/AlJKC3nXr7AJbv2Hc175n/jYLuwfEfdxCfEwhVddQX25KXwq6aZ8JjClN3Z S45aRZyKWrt+6PCF0OCxsBsd6WbRrBNTxkGoxwhCVXP+5zGaxpk7yxu0tsPcUt6Mo7DM L51ElXZLD+7HqWdUkSPZZvo2rUq2l5PfsbtvlrVkSzseXjgpQy0aaC16f9u+CGqTyBsz QmrB3Xy+1sSKhVV7A1me9SYPXfuokNmtkV3xaOahX0ZDX7SIz+1BbC3PQ2x5KenY1WVb g/NVW88UiKYnRdycV2aRKPXUwHDXj2WR45A62cx8rScU91rxfokqNwgwpFyaR3RUkZVM Hu5w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=rlRsJJi7P3ntkMcQCUea3lyipPhHID8kdCGeGyjLvzc=; b=uCR3K7+SUKNG09aazt/I1/rZx3vtKcptXJ2CcuDudrbIK/YqbWUpQW2fiZWH/PXlXP BJB9+/3WRdY6xxPDS1Gsmh13sUFqpR+0DSP4TJyJ/ALH07dgIiWWlfpVpIwmTzH8QOe7 7nKiZDKXFLm42OPUXptLaUsFLVtA5+Z2xZ15InXpehBOKn1rqvNxNID8haetArXPF/VV DNILI+qS4Y5/j2ngPImE/5ZPwAohwtLbjPSqT+7m/Kk+9KaqiIWrJ3OY795PK5Yztfuq kig4Kpp/qaa5cZAlW+RUJSuOAyvXZCDzUeg5lCnl/rpCU5PwNvJd96yaU847TYy8bFP+ 63Jw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="y/FUaioG"; spf=pass (google.com: best guess record for domain of stable-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id 77si35906560pft.72.2019.04.15.12.08.55; Mon, 15 Apr 2019 12:08:55 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of stable-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b="y/FUaioG"; spf=pass (google.com: best guess record for domain of stable-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=stable-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730573AbfDOTIx (ORCPT + 14 others); Mon, 15 Apr 2019 15:08:53 -0400 Received: from mail.kernel.org ([198.145.29.99]:44428 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730590AbfDOTIx (ORCPT ); Mon, 15 Apr 2019 15:08:53 -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 C93292087C; Mon, 15 Apr 2019 19:08:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555355332; bh=2d021XjXqrApmCc0tAWeYZHebctEUMdgkcjJfV2+07I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=y/FUaioG1p/3QL0u1RPySuI5EY9iVNFiNAJW/jOR/tkRBqUdrVicEARLc9M++BUQI zRggBzIzspJRacalIbygivcq59HVw5b9mcSSs/U8cnYYJw+ay0IVgZXsr6lGUG+ITt GgOzgFurnE86fwbVLid5ohUJFY1hog7Zvh20usws= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, stable@kernel.org, Will Deacon Subject: [PATCH 4.19 080/101] arm64: futex: Fix FUTEX_WAKE_OP atomic ops with non-zero result value Date: Mon, 15 Apr 2019 20:59:18 +0200 Message-Id: <20190415183744.658684353@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190415183740.341577907@linuxfoundation.org> References: <20190415183740.341577907@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: Will Deacon commit 045afc24124d80c6998d9c770844c67912083506 upstream. Rather embarrassingly, our futex() FUTEX_WAKE_OP implementation doesn't explicitly set the return value on the non-faulting path and instead leaves it holding the result of the underlying atomic operation. This means that any FUTEX_WAKE_OP atomic operation which computes a non-zero value will be reported as having failed. Regrettably, I wrote the buggy code back in 2011 and it was upstreamed as part of the initial arm64 support in 2012. The reasons we appear to get away with this are: 1. FUTEX_WAKE_OP is rarely used and therefore doesn't appear to get exercised by futex() test applications 2. If the result of the atomic operation is zero, the system call behaves correctly 3. Prior to version 2.25, the only operation used by GLIBC set the futex to zero, and therefore worked as expected. From 2.25 onwards, FUTEX_WAKE_OP is not used by GLIBC at all. Fix the implementation by ensuring that the return value is either 0 to indicate that the atomic operation completed successfully, or -EFAULT if we encountered a fault when accessing the user mapping. Cc: Fixes: 6170a97460db ("arm64: Atomic operations") Signed-off-by: Will Deacon Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/futex.h | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -30,8 +30,8 @@ do { \ " prfm pstl1strm, %2\n" \ "1: ldxr %w1, %2\n" \ insn "\n" \ -"2: stlxr %w3, %w0, %2\n" \ -" cbnz %w3, 1b\n" \ +"2: stlxr %w0, %w3, %2\n" \ +" cbnz %w0, 1b\n" \ " dmb ish\n" \ "3:\n" \ " .pushsection .fixup,\"ax\"\n" \ @@ -50,30 +50,30 @@ do { \ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) { - int oldval = 0, ret, tmp; + int oldval, ret, tmp; u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); pagefault_disable(); switch (op) { case FUTEX_OP_SET: - __futex_atomic_op("mov %w0, %w4", + __futex_atomic_op("mov %w3, %w4", ret, oldval, uaddr, tmp, oparg); break; case FUTEX_OP_ADD: - __futex_atomic_op("add %w0, %w1, %w4", + __futex_atomic_op("add %w3, %w1, %w4", ret, oldval, uaddr, tmp, oparg); break; case FUTEX_OP_OR: - __futex_atomic_op("orr %w0, %w1, %w4", + __futex_atomic_op("orr %w3, %w1, %w4", ret, oldval, uaddr, tmp, oparg); break; case FUTEX_OP_ANDN: - __futex_atomic_op("and %w0, %w1, %w4", + __futex_atomic_op("and %w3, %w1, %w4", ret, oldval, uaddr, tmp, ~oparg); break; case FUTEX_OP_XOR: - __futex_atomic_op("eor %w0, %w1, %w4", + __futex_atomic_op("eor %w3, %w1, %w4", ret, oldval, uaddr, tmp, oparg); break; default: