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 X-Spam-Level: X-Spam-Status: No, score=-2.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01E88C433B4 for ; Tue, 11 May 2021 15:52:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 5569D6188B for ; Tue, 11 May 2021 15:52:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5569D6188B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 63C106B006E; Tue, 11 May 2021 11:52:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 5EB136B0070; Tue, 11 May 2021 11:52:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4D9CB6B0072; Tue, 11 May 2021 11:52:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0182.hostedemail.com [216.40.44.182]) by kanga.kvack.org (Postfix) with ESMTP id 32F746B006E for ; Tue, 11 May 2021 11:52:48 -0400 (EDT) Received: from smtpin02.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E8C2D180B3087 for ; Tue, 11 May 2021 15:52:47 +0000 (UTC) X-FDA: 78129393174.02.D6072B7 Received: from mail-qk1-f181.google.com (mail-qk1-f181.google.com [209.85.222.181]) by imf04.hostedemail.com (Postfix) with ESMTP id 5EBCC3DC for ; Tue, 11 May 2021 15:52:41 +0000 (UTC) Received: by mail-qk1-f181.google.com with SMTP id i67so19188907qkc.4 for ; Tue, 11 May 2021 08:52:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:from:date:message-id:subject:to:cc; bh=hbF2LpdKADXRGlan+ydltTIJ8V3IZlNzIej8e6y1EIg=; b=rI8uKCiuAWozYtPz0pC3x/Xkb2g62pRL+LEEDGWAkc6AdIga9zHph+9tnH/EOq6sOw kn7sgnaJzo0gBHNUywxxd1oF4bck/Dh+yUhpkYiXFWHulQkzWm303JUMG/a1Q5aIZG/8 LCx9p8EJbz3baKr2xdioHRjGVK8+LFQZ/DA573+wHCHO5CQnrvuIJdkTA5G5FCb8SFzs 7g8bU8UFhMSqWSqnZivc7i+jFp6kw+RFd2yJvq40B0PJCqe/E5bkh35nM/geVE7tbjde OxKkb5FgUjLDVyEcgxTXyzjOoF5DlONH/vIBX9L5IjAK/bIVWr/R1BdMriJ0UsQEeMmh xqdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=hbF2LpdKADXRGlan+ydltTIJ8V3IZlNzIej8e6y1EIg=; b=gQEv00rmGH/ldY/O0PXr6HA4NFe5xSXCu5B3H9CK+P4KzjHl7WHU3QbK52AQswHEgP 4/sCC8ucVbZq1qR6ma9NF6PD36roIzgsA0GY4z8AvCdSEhj9eY6mVLidPDDWhu1x40ie fPwXrY++AOLnqMTBrjVq/LgwlfJuKUh3Tsf4KajNMimiGyYuogiOZEZEQdOU1rzT01TA sIGdRcCSoTGuaV68v0darMpfMFrDis11ID4Wp15Xm+aMTaRSSn9yAgESXt7W2UtmMJb1 wYflHeJ58E4dpxbZ7bTGQ5uOX4x62eEoGPVAkJb8egFf/G/B57h8D7isHGVDfI/8FFZE 1dmw== X-Gm-Message-State: AOAM532GQIRX5t3zTyJ0yxMDSPdjb4/X/ixPYxzX4t0XrVVoI0Zd2VwP EtGGl0vWfhIKo60mu6X6iF6T3lQJY6WtOD1QtOckW1U1cpo= X-Google-Smtp-Source: ABdhPJxNaAH4z6gpc5+vJZgh847Ew5wJf045e+eW/iMf8z29eAKdTFs053VrcQbU8FzgDs9slxmz2tz13nJp1CwFUxo= X-Received: by 2002:a37:a506:: with SMTP id o6mr28305286qke.462.1620748366544; Tue, 11 May 2021 08:52:46 -0700 (PDT) MIME-Version: 1.0 From: Derrick McKee Date: Tue, 11 May 2021 11:52:35 -0400 Message-ID: Subject: slab_alloc_node with CONFIG_SLAB_FREELIST_HARDENED To: Linux Memory Management List Cc: cl@linux.com, penberg@kernel.org, rientjes@google.com, iamjoonsoo.kim@lge.com, Andrew Morton Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 5EBCC3DC Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gmail.com header.s=20161025 header.b=rI8uKCiu; spf=pass (imf04.hostedemail.com: domain of derrickmckee@gmail.com designates 209.85.222.181 as permitted sender) smtp.mailfrom=derrickmckee@gmail.com; dmarc=pass (policy=none) header.from=gmail.com X-Rspamd-Server: rspam04 X-Stat-Signature: i4xa1p31eo3mnjdee597ztjdjuu1sofd Received-SPF: none (gmail.com>: No applicable sender policy available) receiver=imf04; identity=mailfrom; envelope-from=""; helo=mail-qk1-f181.google.com; client-ip=209.85.222.181 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1620748361-401099 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi, I am trying to understand how slab_alloc_node works in mm/slub.c when CONFIG_SLAB_FREELIST_HARDENED=y. It seems like in ___slab_alloc, c->freelist gets assigned the result of get_freepointer, which, when CONFIG_SLAB_FREELIST_HARDENED=y, returns a value XOR'd with a per-cache random number. However, that XOR'd value is never seemingly undone, and slab_alloc_node passes the XOR'd (and thus invalid) pointer directly to get_freepointer. Does anyone know where the XOR reversal is performed? Thanks. -- Derrick McKee