From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id 49A396B0005 for ; Wed, 14 Feb 2018 15:45:56 -0500 (EST) Received: by mail-it0-f70.google.com with SMTP id y187so13333521itc.8 for ; Wed, 14 Feb 2018 12:45:56 -0800 (PST) Received: from smtprelay.hostedemail.com (smtprelay0141.hostedemail.com. [216.40.44.141]) by mx.google.com with ESMTPS id v3si1951876itf.20.2018.02.14.12.45.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 14 Feb 2018 12:45:55 -0800 (PST) Message-ID: <1518641152.3678.28.camel@perches.com> Subject: Re: [PATCH v2 2/8] mm: Add kvmalloc_ab_c and kvzalloc_struct From: Joe Perches Date: Wed, 14 Feb 2018 12:45:52 -0800 In-Reply-To: <20180214201154.10186-3-willy@infradead.org> References: <20180214201154.10186-1-willy@infradead.org> <20180214201154.10186-3-willy@infradead.org> Content-Type: text/plain; charset="ISO-8859-1" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox , Andrew Morton Cc: Matthew Wilcox , linux-mm@kvack.org, Kees Cook , linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com On Wed, 2018-02-14 at 12:11 -0800, Matthew Wilcox wrote: > From: Matthew Wilcox > > We have kvmalloc_array in order to safely allocate an array with a > number of elements specified by userspace (avoiding arithmetic overflow > leading to a buffer overrun). But it's fairly common to have a header > in front of that array (eg specifying the length of the array), so we > need a helper function for that situation. > > kvmalloc_ab_c() is the workhorse that does the calculation, but in spite > of our best efforts to name the arguments, it's really hard to remember > which order to put the arguments in. kvzalloc_struct() eliminates that > effort; you tell it about the struct you're allocating, and it puts the > arguments in the right order for you (and checks that the arguments > you've given are at least plausible). > > For comparison between the three schemes: > > sev = kvzalloc(sizeof(*sev) + sizeof(struct v4l2_kevent) * elems, > GFP_KERNEL); > sev = kvzalloc_ab_c(elems, sizeof(struct v4l2_kevent), sizeof(*sev), > GFP_KERNEL); > sev = kvzalloc_struct(sev, events, elems, GFP_KERNEL); Perhaps kv[zm]alloc_buf_and_array is better naming. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org