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 BBEBBC433F5 for ; Fri, 25 Mar 2022 13:15:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2F4C26B0071; Fri, 25 Mar 2022 09:15:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A3E16B0073; Fri, 25 Mar 2022 09:15:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1444A6B0074; Fri, 25 Mar 2022 09:15:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0162.hostedemail.com [216.40.44.162]) by kanga.kvack.org (Postfix) with ESMTP id 045936B0071 for ; Fri, 25 Mar 2022 09:15:52 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 9D3C3A5D5E for ; Fri, 25 Mar 2022 13:15:51 +0000 (UTC) X-FDA: 79282956102.27.B429340 Received: from mail-yb1-f173.google.com (mail-yb1-f173.google.com [209.85.219.173]) by imf23.hostedemail.com (Postfix) with ESMTP id 1C8E0140005 for ; Fri, 25 Mar 2022 13:15:50 +0000 (UTC) Received: by mail-yb1-f173.google.com with SMTP id v35so13957889ybi.10 for ; Fri, 25 Mar 2022 06:15:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=UVtmrpcYjsoxSNLprgvqR2q01AjSQZrSDBr9I2ujCrQ=; b=QunYh1X/vTWnm4E2/+QnA1pxI/i0Uo9LkqQfRz546sb9EOHXd8Vt+ShyU5kgd8ShBt peD0c61RkIzaxF0G9jkb/arKNspB0OeVJLspXCh/mJFP/m5gcxMksfvptI8eN7Jf4C4R 1TQqwv9UubymjB2lHqOrLGPPBPluo2Ey1TYWiXGKeayHXMgiLpaxS7w2nY9AnyhGLRKi Gql3YU231CDmpycokTqC7ylPkkLOBeZz9uBhRfndabW/olS8mFGJzcH78T6CmCTAEo/5 9lNcyGHWMvRMA69qw2qeBbMJ+zdBwV6V8e9Be99rMPwACAm6BLQYemx1tZNY6AN99z5+ h8xw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=UVtmrpcYjsoxSNLprgvqR2q01AjSQZrSDBr9I2ujCrQ=; b=X0b4kNN67nCgLkPb/okiZKT6FsYV75oLp7/vwK/3KFw6stAFxZbtnleKxxMVVESBEW dpQT496FvMOKb1eYoAc9OfZqXh3QSaPofCcnc73yaaaGthPVdEvWXx3vQ0fprzlFUeA7 /vWC5MTm6k0NzJ++h3f5NWwEWOZNuEKmtPRuKxYocK9dYEGCch15vRX0Ea3j9Id0p/Nb nOblh8XVCgX+nWITfRC7F2zUTL7o2k0YS3SVhjmFQNOcwUdY3lnKC8JfQ35/5nN9DlxJ tBuhoTRLp29ruSwsa6bS+CY8s3G/3/T+8KsfJwqhMX4NMJWnTqS0sl5lEFrNT+hQ6T5s GbDg== X-Gm-Message-State: AOAM532P1Z/CpH5dOJLnMooO3XUbKME/RZGm2z19o6t37sd2IYolF9yC UsWfUsBildImY1RuyGpQGGGAJ20on8oMJ6ZKqx/Kag== X-Google-Smtp-Source: ABdhPJw8jLmmkYMWCtGyb9SAEyWAmdLtUxmnI6j62OH72T/JezNOHDJSuka8BG+J+OQWwYh7kxgvHCtXaMopGrq5oY0= X-Received: by 2002:a25:3750:0:b0:634:6b89:ca9f with SMTP id e77-20020a253750000000b006346b89ca9fmr9903674yba.363.1648214150074; Fri, 25 Mar 2022 06:15:50 -0700 (PDT) MIME-Version: 1.0 References: <20211214162050.660953-1-glider@google.com> <20211214162050.660953-17-glider@google.com> <82de6739-a070-695b-bbc8-dfa931aa5e00@suse.cz> In-Reply-To: <82de6739-a070-695b-bbc8-dfa931aa5e00@suse.cz> From: Alexander Potapenko Date: Fri, 25 Mar 2022 14:15:13 +0100 Message-ID: Subject: Re: [PATCH 16/43] kmsan: mm: call KMSAN hooks from SLUB code To: Vlastimil Babka Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Ard Biesheuvel , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Linux Memory Management List , Linux-Arch , LKML Content-Type: text/plain; charset="UTF-8" X-Rspam-User: Authentication-Results: imf23.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b="QunYh1X/"; spf=pass (imf23.hostedemail.com: domain of glider@google.com designates 209.85.219.173 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1C8E0140005 X-Stat-Signature: po59n8hg8tpqq6suqurcfufyods8b83f X-HE-Tag: 1648214150-339589 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: > > static inline void *get_freepointer(struct kmem_cache *s, void *object) > > { > > object = kasan_reset_tag(object); > > - return freelist_dereference(s, object + s->offset); > > + return kmsan_init(freelist_dereference(s, object + s->offset)); > > ... but I don't see why it applies to get_freepointer() too? What am I missing? Agreed, kmsan_init() is not needed here. > > } > > > > static void prefetch_freepointer(const struct kmem_cache *s, void *object) > > @@ -357,18 +361,28 @@ static void prefetch_freepointer(const struct kmem_cache *s, void *object) > > prefetchw(object + s->offset); > > } > > > > +/* > > + * When running under KMSAN, get_freepointer_safe() may return an uninitialized > > + * pointer value in the case the current thread loses the race for the next > > + * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in > > + * slab_alloc_node() will fail, so the uninitialized value won't be used, but > > + * KMSAN will still check all arguments of cmpxchg because of imperfect > > + * handling of inline assembly. > > + * To work around this problem, use kmsan_init() to force initialize the > > + * return value of get_freepointer_safe(). > > + */ > > static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) > > { > > unsigned long freepointer_addr; > > void *p; > > > > if (!debug_pagealloc_enabled_static()) > > - return get_freepointer(s, object); > > + return kmsan_init(get_freepointer(s, object)); > > So here kmsan_init() is done twice? Yeah, removing it from get_freepointer() does not introduce new errors. I'll fix this in v2.