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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 165C4C10F11 for ; Wed, 24 Apr 2019 17:47:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D08AE218B0 for ; Wed, 24 Apr 2019 17:47:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556128065; bh=xm9ei95JbKMxxDCtd2eG0BR8le4JJv/5MyDXMBhYaqM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=0DTxaVxyGYpw8hg5p84bf1qtanfbXghz5mCoLfg9pr0dBvkS/tLosydnN9sl0+iX8 25PgzQEGS9OKtVdM0is+6zto3U3BWB6Pf83VahmICCSMH+hEjhhUVjl5UJu1X+jLMe /fMfOHe0aM6x5tPQTLV1wt5KuJiryJ/FePwVNmAU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391279AbfDXRbv (ORCPT ); Wed, 24 Apr 2019 13:31:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:58344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391273AbfDXRbt (ORCPT ); Wed, 24 Apr 2019 13:31:49 -0400 Received: from localhost (62-193-50-229.as16211.net [62.193.50.229]) (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 50F9E21903; Wed, 24 Apr 2019 17:31:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1556127108; bh=xm9ei95JbKMxxDCtd2eG0BR8le4JJv/5MyDXMBhYaqM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=P49Tu6DOpp3O6WNh65OBteAddrbSH6b/q06f5Xet3PPKQYJcJv6MKMolSlzE/sbxK YcoqW2ny+iW3WhhfWH+xORgzA3eAFcRcg52QKswOASv5//gIH9HfTyVio7kjUIdQ6m N0Apw6Cs3U1j4tJhApGQIj4Hew1FCuruZTqdQTNs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nathan Chancellor , Catalin Marinas Subject: [PATCH 4.19 65/96] arm64: futex: Restore oldval initialization to work around buggy compilers Date: Wed, 24 Apr 2019 19:10:10 +0200 Message-Id: <20190424170924.131665768@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190424170919.829037226@linuxfoundation.org> References: <20190424170919.829037226@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nathan Chancellor commit ff8acf929014b7f87315588e0daf8597c8aa9d1c upstream. Commit 045afc24124d ("arm64: futex: Fix FUTEX_WAKE_OP atomic ops with non-zero result value") removed oldval's zero initialization in arch_futex_atomic_op_inuser because it is not necessary. Unfortunately, Android's arm64 GCC 4.9.4 [1] does not agree: ../kernel/futex.c: In function 'do_futex': ../kernel/futex.c:1658:17: warning: 'oldval' may be used uninitialized in this function [-Wmaybe-uninitialized] return oldval == cmparg; ^ In file included from ../kernel/futex.c:73:0: ../arch/arm64/include/asm/futex.h:53:6: note: 'oldval' was declared here int oldval, ret, tmp; ^ GCC fails to follow that when ret is non-zero, futex_atomic_op_inuser returns right away, avoiding the uninitialized use that it claims. Restoring the zero initialization works around this issue. [1]: https://android.googlesource.com/platform/prebuilts/gcc/linux-x86/aarch64/aarch64-linux-android-4.9/ Cc: stable@vger.kernel.org Fixes: 045afc24124d ("arm64: futex: Fix FUTEX_WAKE_OP atomic ops with non-zero result value") Reviewed-by: Greg Kroah-Hartman Signed-off-by: Nathan Chancellor Signed-off-by: Catalin Marinas Signed-off-by: Greg Kroah-Hartman --- arch/arm64/include/asm/futex.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/arm64/include/asm/futex.h +++ b/arch/arm64/include/asm/futex.h @@ -50,7 +50,7 @@ do { \ static inline int arch_futex_atomic_op_inuser(int op, int oparg, int *oval, u32 __user *_uaddr) { - int oldval, ret, tmp; + int oldval = 0, ret, tmp; u32 __user *uaddr = __uaccess_mask_ptr(_uaddr); pagefault_disable();