From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELulnoJ+oWOLmJrcxDyalKERHsgpifZaV9l83+n15E8Sb4BubOWzvL6b1+pTc8BpnBjJJ0DH ARC-Seal: i=1; a=rsa-sha256; t=1520575201; cv=none; d=google.com; s=arc-20160816; b=dqrQ/bRNlsUqUCFRgTw6n95W2I9EC2euIM3+6cszmkuwanJo3OFsSlaAYWBserklmJ XJYoBe6GP47qGswRGn8C3HsNBm7tHFvAQp29zCRXnHm2XtOiBF17IkjarweXxHln/cH7 rmsu+FkWve+ZlWmSkpCUid1sMuCmlZrEqmtz8BXHEasD666hFUnQqJPrDChCJYUjvazA 0cO/AI7MS0qMAreZtR2dDchlzECPMb/IDQ+Ec2zPGj2m80AGmWqwl+y3Ygb3PxqWKDAa q7uQ8jkAj6Oaxf34HOTCogKOa9OpAqXqVoHTcMnyKZwdRrKyOtZNzsYauHkTmnhuVK71 3icw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:message-id:in-reply-to:subject :cc:to:from:date:delivered-to:list-id:list-subscribe :list-unsubscribe:list-help:list-post:precedence:mailing-list :arc-authentication-results; bh=Z9wC4DtB3ydCxa4u/X0ZOMazTsEsAl6Jt/aRjzR4l1o=; b=kDtJ+kly3Z1K4EeYZrtYs7GcNRv+vk+I6xjvF+uJW/2RzsQi+XriNg52QuKrZlWMKv aMThEbye1zbLq9WHQnzTBnpyLTOdzrjU2SchR++7FBNwMC8RjCRAoR2nIGhnlYMCN1KI H8/tW18bL21rjxvhKI4qGhNM/9putjPX39uWyMYKc+jRi8sJAQYUrN7tEBk+ZfJtkhXp 33DmJmNtlrID4MSl7D+WhdPAClfB9xQ4b0XxZC0GOsgyG248oRLyijpR+ScyanEBloz1 fvkxC/+ek90GtL+GBEOeKmszQpUIQ8HNMTTYAEe1qJGhz2NBGaCRuLL0pYZMCnNU+cAB pX+g== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12296-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12296-gregkh=linuxfoundation.org@lists.openwall.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of kernel-hardening-return-12296-gregkh=linuxfoundation.org@lists.openwall.com designates 195.42.179.200 as permitted sender) smtp.mailfrom=kernel-hardening-return-12296-gregkh=linuxfoundation.org@lists.openwall.com Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm List-Post: List-Help: List-Unsubscribe: List-Subscribe: X-IronPort-AV: E=Sophos;i="5.47,444,1515452400"; d="scan'208";a="317141657" Date: Fri, 9 Mar 2018 06:59:43 +0100 (CET) From: Julia Lawall X-X-Sender: jll@hadrien To: Matthew Wilcox cc: Kees Cook , Andrew Morton , Matthew Wilcox , Linux-MM , LKML , Kernel Hardening , cocci@systeme.lip6.fr, Himanshu Jha Subject: Re: [PATCH 2/2] mm: Add kvmalloc_ab_c and kvzalloc_struct In-Reply-To: <20180308230512.GD29073@bombadil.infradead.org> Message-ID: References: <20180214182618.14627-1-willy@infradead.org> <20180214182618.14627-3-willy@infradead.org> <20180308025812.GA9082@bombadil.infradead.org> <20180308230512.GD29073@bombadil.infradead.org> User-Agent: Alpine 2.20 (DEB 67 2015-01-07) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1592401933337716102?= X-GMAIL-MSGID: =?utf-8?q?1594438662530146007?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, 8 Mar 2018, Matthew Wilcox wrote: > On Thu, Mar 08, 2018 at 07:24:47AM +0100, Julia Lawall wrote: > > On Wed, 7 Mar 2018, Matthew Wilcox wrote: > > > On Wed, Mar 07, 2018 at 10:18:21PM +0100, Julia Lawall wrote: > > > > > Otherwise, yes, please. We could build a coccinelle rule for > > > > > additional replacements... > > > > > > > > A potential semantic patch and the changes it generates are attached > > > > below. Himanshu Jha helped with its development. Working on this > > > > uncovered one bug, where the allocated array is too large, because the > > > > size provided for it was a structure size, but actually only pointers to > > > > that structure were to be stored in it. > > > > > > This is cool! Thanks for doing the coccinelle patch! Diffstat: > > > > > > 50 files changed, 81 insertions(+), 124 deletions(-) > > > > > > I find that pretty compelling. I'll repost the kvmalloc_struct patch > > > imminently. > > > > Thanks. So it's OK to replace kmalloc and kzalloc, even though they > > didn't previously consider vmalloc and even though kmalloc doesn't zero? > > We'll also need to replace the corresponding places where those structs > are freed with kvfree(). Can coccinelle handle that too? This would be harder to do 100% reliably. Coccinelle would have to rely on the structure name or the structure type, if the free is in a different function. But I guess that the type should be mostly reliable, since all instances of allocations of the same type should be transformed in the same way. > > > There are a few other cases that use GFP_NOFS and GFP_NOWAIT, but I didn't > > transform those because the comment says that the flags should be > > GFP_KERNEL based. Should those be transformed too? > > The problem with non-GFP_KERNEL allocations is that vmalloc may have to > allocate page tables, which is always done with an implicit GFP_KERNEL > allocation. There's an intent to get rid of GFP_NOFS, but that's not > been realised yet (and I'm not sure of our strategy to eliminate it ... > I'll send a separate email about that). I'm not sure why anything's > trying to allocate with GFP_NOWAIT; can you send a list of those places? drivers/dma/fsl-edma.c: fsl_desc = kzalloc(sizeof(*fsl_desc) + sizeof(struct fsl_edma_sw_tcd) * sg_len, GFP_NOWAIT); drivers/dma/st_fdma.c: fdesc = kzalloc(sizeof(*fdesc) + sizeof(struct st_fdma_sw_node) * sg_len, GFP_NOWAIT); drivers/dma/pxa_dma.c: sw_desc = kzalloc(sizeof(*sw_desc) + nb_hw_desc * sizeof(struct pxad_desc_hw *), GFP_NOWAIT); julia