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 08E01C433FE for ; Sat, 8 Oct 2022 18:16:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 33FD56B0072; Sat, 8 Oct 2022 14:16:34 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2EF6D6B0073; Sat, 8 Oct 2022 14:16:34 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 190556B0074; Sat, 8 Oct 2022 14:16:34 -0400 (EDT) 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 031546B0072 for ; Sat, 8 Oct 2022 14:16:33 -0400 (EDT) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id C82AAC04B9 for ; Sat, 8 Oct 2022 18:16:33 +0000 (UTC) X-FDA: 79998587466.24.F5471E7 Received: from mga01.intel.com (mga01.intel.com [192.55.52.88]) by imf28.hostedemail.com (Postfix) with ESMTP id 42ABFC0029 for ; Sat, 8 Oct 2022 18:16:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1665252992; x=1696788992; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Q7YlJwn22ePcF+UsrTEOpg8IcVNJxX9fgtN3uSim9/E=; b=M2yxEwpfXuAxdHwKzCaJJrCRbtX4j3oUsf4fQqIqkutxIhYMWfSvpYzH eVhTL7NBsd7MyJ39OnUXSkREwKmAJUzPQrUAEnUECQKqg5EnkjMhdSEpB 5PJRY4u5+qAOzvuwQ5nKbLiD6Hsw7VZJM0TQQqyiM8JWrNb18Ed6vIJm6 NmwcVVl8newGwn/iqp4AyqZNF4Ba9nAYZQD5mW6yTA2a5EkadqRt4FOV/ QUmfU93+fl4WN0BTpWfsXQ2KPtZhogRilTTVEjI8dzv2Uhw7N2QQFJ3I1 tMXmrlTOeKKjzzPESbwuJJZpbFf67L3R25fBdKK77MyBS/dz29i6wMeQ/ g==; X-IronPort-AV: E=McAfee;i="6500,9779,10494"; a="330422118" X-IronPort-AV: E=Sophos;i="5.95,170,1661842800"; d="scan'208";a="330422118" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Oct 2022 11:16:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10494"; a="750899918" X-IronPort-AV: E=Sophos;i="5.95,170,1661842800"; d="scan'208";a="750899918" Received: from smile.fi.intel.com ([10.237.72.54]) by orsmga004.jf.intel.com with ESMTP; 08 Oct 2022 11:16:23 -0700 Received: from andy by smile.fi.intel.com with local (Exim 4.96) (envelope-from ) id 1ohEN3-0048ft-0Q; Sat, 08 Oct 2022 21:16:21 +0300 Date: Sat, 8 Oct 2022 21:16:20 +0300 From: Andy Shevchenko To: Kees Cook Cc: "Jason A. Donenfeld" , linux-kernel@vger.kernel.org, patches@lists.linux.dev, dri-devel@lists.freedesktop.org, kasan-dev@googlegroups.com, kernel-janitors@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-block@vger.kernel.org, linux-crypto@vger.kernel.org, linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-media@vger.kernel.org, linux-mips@vger.kernel.org, linux-mm@kvack.org, linux-mmc@vger.kernel.org, linux-mtd@lists.infradead.org, linux-nvme@lists.infradead.org, linux-parisc@vger.kernel.org, linux-rdma@vger.kernel.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, linux-usb@vger.kernel.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, loongarch@lists.linux.dev, netdev@vger.kernel.org, sparclinux@vger.kernel.org, x86@kernel.org, Jan Kara Subject: Re: [PATCH v4 2/6] treewide: use prandom_u32_max() when possible Message-ID: References: <53DD0148-ED15-4294-8496-9E4B4C7AD061@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53DD0148-ED15-4294-8496-9E4B4C7AD061@chromium.org> Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1665252993; 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=gKkERMB1M9xOEPNfE3IrAsq0mJwwY0seKkU7oCng9qc=; b=qTWGfJ2sPrr50G4WOHyEPWOEbO+65ohXf+hvavb+GzKAfSaPzNBjeoZDwzldnfKYA0RInD skJEDO5Wu1s0PbzMhzj1aJjqEtKr42CrsstZP648ve6SnEbjWQIwk/y0mux4Edx7C8Ecf4 aWVMuUFyGH97C5PEfNrDldbCdOo/xtk= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=M2yxEwpf; spf=none (imf28.hostedemail.com: domain of andriy.shevchenko@linux.intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=andriy.shevchenko@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1665252993; a=rsa-sha256; cv=none; b=nBbr9AHyRo4bxoCFwHAz1HFRhik2aYEc3GHXFlL6Yb0H1oiffl5L6T8clNCan5o1sgSaWg 5dcl+HsUeu7RnFahax8MswwZ7/SO4HJcidL9Qy/TvBStGshGuov0YUkY9Mubrm7WSJgkEu 0lJtywNAmx1dSMsrRQzq0q4Bxlk7HR4= Authentication-Results: imf28.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=M2yxEwpf; spf=none (imf28.hostedemail.com: domain of andriy.shevchenko@linux.intel.com has no SPF policy when checking 192.55.52.88) smtp.mailfrom=andriy.shevchenko@linux.intel.com; dmarc=fail reason="No valid SPF" header.from=intel.com (policy=none) X-Rspam-User: X-Stat-Signature: cewgt54adrft9t9u1jm5s8jwfkh94aou X-Rspamd-Queue-Id: 42ABFC0029 X-Rspamd-Server: rspam01 X-HE-Tag: 1665252992-97750 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: On Fri, Oct 07, 2022 at 08:50:43PM -0700, Kees Cook wrote: > On October 7, 2022 7:21:28 PM PDT, "Jason A. Donenfeld" wrote: > >On Fri, Oct 07, 2022 at 03:47:44PM -0700, Kees Cook wrote: > >> On Fri, Oct 07, 2022 at 12:01:03PM -0600, Jason A. Donenfeld wrote: ... > >> These are more fun, but Coccinelle can still do them with a little > >> Pythonic help: > >> > >> // Find a potential literal > >> @literal_mask@ > >> expression LITERAL; > >> identifier randfunc =~ "get_random_int|prandom_u32|get_random_u32"; > >> position p; > >> @@ > >> > >> (randfunc()@p & (LITERAL)) > >> > >> // Add one to the literal. > >> @script:python add_one@ > >> literal << literal_mask.LITERAL; > >> RESULT; > >> @@ > >> > >> if literal.startswith('0x'): > >> value = int(literal, 16) + 1 > >> coccinelle.RESULT = cocci.make_expr("0x%x" % (value)) > >> elif literal[0] in '123456789': > >> value = int(literal, 10) + 1 > >> coccinelle.RESULT = cocci.make_expr("%d" % (value)) > >> else: > >> print("I don't know how to handle: %s" % (literal)) Wouldn't Python take care about (known) prefixes itself? try: x = int(literal) except ValueError as ex: print(..., ex.error) > >> // Replace the literal mask with the calculated result. > >> @plus_one@ > >> expression literal_mask.LITERAL; > >> position literal_mask.p; > >> expression add_one.RESULT; > >> identifier FUNC; > >> @@ > >> > >> - (FUNC()@p & (LITERAL)) > >> + prandom_u32_max(RESULT) > > > >Oh that's pretty cool. I can do the saturation check in python, since > >`value` holds the parsed result. Neat. > > It is (at least how I have it here) just the string, so YMMV. ... > >Thanks a bunch for the guidance. > > Sure thing! I was pleased to figure out how to do the python bit. I believe it can be optimized -- With Best Regards, Andy Shevchenko