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=-19.6 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,T_DKIMWL_WL_MED, USER_IN_DEF_DKIM_WL autolearn=ham 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 DEA53C04AAA for ; Thu, 2 May 2019 16:41:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AA2C920C01 for ; Thu, 2 May 2019 16:41:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="pW9Mlh00" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726524AbfEBQlF (ORCPT ); Thu, 2 May 2019 12:41:05 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:36430 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726268AbfEBQlF (ORCPT ); Thu, 2 May 2019 12:41:05 -0400 Received: by mail-pg1-f195.google.com with SMTP id 85so1316774pgc.3 for ; Thu, 02 May 2019 09:41:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=92karzGId4kTiPxbclHEQu/kjCIMGVKlDvLxWKLPllQ=; b=pW9Mlh00pTbPzKKMewhu5d9r6gm71AyCd5VE3PXTq9/6KeJWTWX9VAdyklQe4wuYb3 hw6/lCKfgP3MBQuvHSNTnDii93JeoAZ1tz36Ilk1XAnuH2tR8iS45vHy63ek7KeVo8Kv pPaZFSX+7KB1/bAO/KXNp2pKUm1C86PLwVWmBVtbE1JqIgA3KIcb1b/b7Ng6bjqelicY 6DQAN7is5Vz8aCc+ZcoCa9As2irNjbQGXPT3N7cDSP18s23973KvWfDy7jubbL2cvXcF 9fU8o6qOaaYqh7iOQW85PTkzEhusyPBLF2Ti3wgqhnyl9L/q3tU0Sq/+WyRxSAFHojV5 aVVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=92karzGId4kTiPxbclHEQu/kjCIMGVKlDvLxWKLPllQ=; b=aDe0Mw5+P0zit0alm2dP5evf5vyzOQKDKv68h5vX7mDZNfZ6sT6aNlQ+E1SklY6Wf2 HoPikNYHKlwGh2pNPxAviEvpOZ5TbXZpt5bP1S1KyFZQZTWID+9m3tuWJxpzWFtqxcIw TOx8Yz288Ig4djbVokOkT8m9gDZEtdCbqzQSc11FEtelW6bvRvA27HnvQw1ait0j+SGL XRDj/lc+9rFnGnlMDqOb1TxsH8Fg0VKVrFthnOnciIHGXvoh9BBEULCu8hvaBJeRLT1j H1yHVWTWBhonk4TqtZUklGKL0lkAj6r7EmZuxGpatzLZyLf4lUsKvNmojzm+VQYPtN81 mVFg== X-Gm-Message-State: APjAAAV5IZ3KTLlpZ7vdzy3kBZsikS/q/AYVadyLNCmUeDWrWQeA/Ald WxbNXj1j2J7zSlDtqnEITRgGZVLoNrCnLtY73V0rYA== X-Google-Smtp-Source: APXvYqxEpi/34FQTQo/i2+QqbKQVsIw9n+cFj3zq5T2pXhuwK8N3k0YF3vpXL1+twKXJJwXv+Ny1FxDYEUV2ic9nRnQ= X-Received: by 2002:a62:46c7:: with SMTP id o68mr5390737pfi.54.1556815263742; Thu, 02 May 2019 09:41:03 -0700 (PDT) MIME-Version: 1.0 References: <20190502153538.2326-1-natechancellor@gmail.com> <20190502163057.6603-1-natechancellor@gmail.com> In-Reply-To: <20190502163057.6603-1-natechancellor@gmail.com> From: Andrey Konovalov Date: Thu, 2 May 2019 18:40:52 +0200 Message-ID: Subject: Re: [PATCH v2] kasan: Initialize tag to 0xff in __kasan_kmalloc To: Nathan Chancellor Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Linux Memory Management List , LKML , Nick Desaulniers , clang-built-linux@googlegroups.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 2, 2019 at 6:31 PM Nathan Chancellor wrote: > > When building with -Wuninitialized and CONFIG_KASAN_SW_TAGS unset, Clang > warns: > > mm/kasan/common.c:484:40: warning: variable 'tag' is uninitialized when > used here [-Wuninitialized] > kasan_unpoison_shadow(set_tag(object, tag), size); > ^~~ > > set_tag ignores tag in this configuration but clang doesn't realize it > at this point in its pipeline, as it points to arch_kasan_set_tag as > being the point where it is used, which will later be expanded to > (void *)(object) without a use of tag. Initialize tag to 0xff, as it > removes this warning and doesn't change the meaning of the code. > > Link: https://github.com/ClangBuiltLinux/linux/issues/465 > Signed-off-by: Nathan Chancellor Reviewed-by: Andrey Konovalov Thanks! > --- > > v1 -> v2: > > * Initialize tag to 0xff at Andrey's request > > mm/kasan/common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 36afcf64e016..242fdc01aaa9 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -464,7 +464,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, > { > unsigned long redzone_start; > unsigned long redzone_end; > - u8 tag; > + u8 tag = 0xff; > > if (gfpflags_allow_blocking(flags)) > quarantine_reduce(); > -- > 2.21.0 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To post to this group, send email to kasan-dev@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20190502163057.6603-1-natechancellor%40gmail.com. > For more options, visit https://groups.google.com/d/optout.