From patchwork Tue May 12 16:36:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Dave Martin X-Patchwork-Id: 11543511 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 11736139A for ; Tue, 12 May 2020 16:38:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AC7FE20714 for ; Tue, 12 May 2020 16:38:10 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="TDmh3RLX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC7FE20714 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:MIME-Version:Cc:List-Subscribe: List-Help:List-Post:List-Archive:List-Unsubscribe:List-Id:References: In-Reply-To:Message-Id:Date:Subject:To:From:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=l/KQpjTUrBE/Nq6fKG+awadFVxEjYiLJ7ECvNM8AdjY=; b=TDmh3RLXbFDVn7FCuprC1lfgct urTptiPAtVL2vYVKKLREugNfsH21C7oFsHKkXbLGo3XfAFdGUl4Nx0A29gh+gYMiTa/xN5dvDQ4qV +ChGrkuMAKxXKw7v0y2pHJnGysSzvBJXcwdeTcYiqKPq2oWTRtzCVzkeGeinXcOPm1hufw7CdTs6I nlYJLohmY45eWj0a5s8S+WZDvGyzrU41CA969AZJFWeKw74yw0O5N929A0MGjCjtvec1G/xA8YUUQ t33+VBjHUcjq/SRTx4Ls1QhxnJvdCNjBSJj7JXmhIBt+eq0g3RhpQnwT1iie8X8yFon56ZjUa73P7 zZPO/Qfw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYXuu-000882-Gu; Tue, 12 May 2020 16:38:04 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jYXud-0007qd-SM for linux-arm-kernel@lists.infradead.org; Tue, 12 May 2020 16:37:49 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 7C404D6E; Tue, 12 May 2020 09:37:47 -0700 (PDT) Received: from e103592.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CA7123F305; Tue, 12 May 2020 09:37:46 -0700 (PDT) From: Dave Martin To: mtk.manpages@gmail.com Subject: [PATCH 02/14] prctl.2: Add health warning Date: Tue, 12 May 2020 17:36:47 +0100 Message-Id: <1589301419-24459-3-git-send-email-Dave.Martin@arm.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1589301419-24459-1-git-send-email-Dave.Martin@arm.com> References: <1589301419-24459-1-git-send-email-Dave.Martin@arm.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200512_093747_952936_2322BABB X-CRM114-Status: UNSURE ( 9.18 ) X-CRM114-Notice: Please train this message. X-Spam-Score: -2.3 (--) X-Spam-Report: SpamAssassin version 3.4.4 on bombadil.infradead.org summary: Content analysis details: (-2.3 points) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at https://www.dnswl.org/, medium trust [217.140.110.172 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 SPF_HELO_NONE SPF: HELO does not publish an SPF Record X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, linux-man@vger.kernel.org, linux-arm-kernel@lists.infradead.org MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org In reality, almost every prctl interferes with assumptions that the compiler and C library / runtime rely on. prctl() can therefore make userspace explode in a variety ways that are likely to be hard to debug. This is not obvious to the uninitiated, so add a warning. Signed-off-by: Dave Martin --- man2/prctl.2 | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/man2/prctl.2 b/man2/prctl.2 index 7932ada..a35b748 100644 --- a/man2/prctl.2 +++ b/man2/prctl.2 @@ -66,6 +66,11 @@ prctl \- operations on a process or thread manipulates various aspects of the behavior of the calling thread or process. .PP +Note that careless use of +.BR prctl () +can confuse the userspace run-time environment, +so these operations should be used with care (if at all). +.PP .BR prctl () is called with a first argument describing what to do (with values defined in \fI\fP), and further