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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id ADA01C46CD2 for ; Wed, 27 Dec 2023 09:56:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id DDE726B0072; Wed, 27 Dec 2023 04:56:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id D8F3C6B0074; Wed, 27 Dec 2023 04:56:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C7D4C6B0075; Wed, 27 Dec 2023 04:56:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id BC3086B0072 for ; Wed, 27 Dec 2023 04:56:46 -0500 (EST) Received: from smtpin28.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7C93BC0680 for ; Wed, 27 Dec 2023 09:56:46 +0000 (UTC) X-FDA: 81612144012.28.A5ED19B Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf03.hostedemail.com (Postfix) with ESMTP id 725782000D for ; Wed, 27 Dec 2023 09:56:43 +0000 (UTC) Authentication-Results: imf03.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=J3rQw10p; dmarc=none; spf=none (imf03.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1703671004; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=zy714SvT+DQeUe4111cxTQNYwzGCyzYcljCEfmIN3GU=; b=kwwHde8qa6QceuhnSdDs1bbDp6nP2I2yoYg2eMUtWiEpvMV+iyem6MA8ROJdDTC3V2srOt 5kpiIkyVAZhUh8ZYenhI6C4MBUxcSG/nXXmHdxPrt1PJq0jW7nLdKareriZqkd5BZb2cc8 VH4tFqRn6Fd5UhJTPTvLBAQAJpPHVrw= ARC-Authentication-Results: i=1; imf03.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=J3rQw10p; dmarc=none; spf=none (imf03.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1703671004; a=rsa-sha256; cv=none; b=EtJiOpUSgqr0yIG6zEecs5cIns5CJFcLMrnr4Ab/p5g9L2u4YBEtXHSgbB6upOcp7tJzaO TUyfMoBnuqnOtf1P4NLwAdKxWwC/31NvGqRGX0Bu8vJ2fEISwOdAGUjLcwyWg/KgKpVwJe UnoYgmpxmb2iqvuvtanG6hhQ4h5l9XY= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=zy714SvT+DQeUe4111cxTQNYwzGCyzYcljCEfmIN3GU=; b=J3rQw10p6C7CX49UsXweFs1cNn gVz02pGjxc+pgEAJH3mTDQmPaR3lBr9hi0VJJ0VGjC7qpUlnsl/uGmVhDoneemf+g5noLNGLopWQm NtORqDXsAH6dYYP1vUJxq/M/RJvcKYVAPKXgqGiEaBuk9MlS5UkiDec3yChcuA63niL4BSGDgAk0T pkFdC3opykDnmNsLfCQwxnnJttskyKqTzU3/W/jIMJqBXZ8s3AtaG0AFozVaaW2OGlVVEJDe3TruO ULdZXrsHPoCOg6bnjl24y0OCxKUmnbYOEkrKZF35n8DnkLNeEgqtI7HKm5Ncp8vZJp2zfid4EtAUm DhH5wSBg==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rIQeU-002aB4-7Y; Wed, 27 Dec 2023 09:56:38 +0000 Date: Wed, 27 Dec 2023 09:56:38 +0000 From: Matthew Wilcox To: Xiaobing Luo Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/cma: change print format of pointer in pr_debug() With %p, the pointer will be hashed and print (____ptrval____) instead. Message-ID: References: <20231227061825.116177-1-luoxiaobing0926@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231227061825.116177-1-luoxiaobing0926@gmail.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 725782000D X-Stat-Signature: 5ckdae3o1co4zf6bbzxt3y5j6mweisg8 X-HE-Tag: 1703671003-415866 X-HE-Meta: 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 Sr7rStPd NfO9MjS+8bo4i/Zw3Wmezu4oPre42tCTxOiNRB1lyINl5hZIy9AAyC1Jr1UyHe3Ib0aWeeIZAuTH3Vg4JQNPtHJWNmj4goLCowWiiUNEWs4tLXpXxp7El3fd4uOWST6kW0dQYOwuGRNml2eNar9A5aFeksGr0xfETVigTh86LN1GynKlB0QnMdluMTvIMTUWsI/obPfFUlCbKORidjqEk0YFidg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Dec 27, 2023 at 06:18:25AM +0000, Xiaobing Luo wrote: > [ 0.070467] cma: cma_alloc(cma (____ptrval____), count 256, align 8) > [ 0.073003] cma: cma_alloc(): returned (____ptrval____) > > Use 0x%px instead of %p to print the pointer. Then the print will be like: > > [ 0.054963] cma: cma_alloc(cma 0xffffffde9ad42a60, count 256, align 8) > [ 0.057385] cma: cma_alloc(): returned 0xfffffffe003b0000 Please explain why we should leak this information to userspace, making it easy for an attacker?