From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 115609 invoked by alias); 19 Mar 2018 14:01:01 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 115594 invoked by uid 89); 19 Mar 2018 14:01:01 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL,BAYES_00,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_PASS autolearn=ham version=3.3.2 spammy= X-HELO: mail-lf0-f68.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=6jJd95MPGWhlrjG+u+arCQbvYeVbA+kqLf+LjqUAB+s=; b=C7v0IO62Q7JjFlQzKrv1NZazt7LKjVd2kJlr5ORxrLRKYWS3oNGlNiZp/oQ8oNKgLU 3c0v0sczNeT59OVPZhnFI0YEatOhUVH+9mDsSrU/L+9IVT6WagBB2MZtM3pHHP9XFTyX 4SLwu4epPtl596XwLL++UgVUL7mZWh5pThZpogW/Csh8Dwi1MUTiqhJwf27JCz+aDhl5 p1KyxamQmlnZUx1DGWoZQ5ZBhXXF8d3HGOO1ZcQZc5+CSnbJNhMLXSwI+3JJJ/hwEiVe /WKfsFiZ3WePieJksSEuX+3yINkKssy3vPi7w2JmoWiEB/5cS0DmUVvQ5JG/HtiZ37V9 eQVQ== X-Gm-Message-State: AElRT7GiphiacvZ/wOBhzBPyxyOvE0VqWyGbCWSduZ+6ZJUpbItEJNVv nvM6NeoBAtwpmS4FBVLFs9awrtMioK46VJaEAxE= X-Google-Smtp-Source: AG47ELuZun9HGPKC4uik9260rfURWTuC2icofEHXWes7fj7qMKRwsHuUaSM60HUtEs1xdhpYKfSFTeNqU09hdeBjOGw= X-Received: by 10.46.69.85 with SMTP id s82mr7893623lja.19.1521468043617; Mon, 19 Mar 2018 07:00:43 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <597954a1-85da-e524-1454-27c46af57413@redhat.com> References: <597954a1-85da-e524-1454-27c46af57413@redhat.com> From: Andrew Senkevich Date: Mon, 19 Mar 2018 14:01:00 -0000 Message-ID: Subject: Re: [PATCH] Fix i386 memmove issue [BZ #22644] To: Florian Weimer Cc: Andreas Schwab , "H.J. Lu" , libc-alpha , Max Horn , thomas@grindinggear.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-SW-Source: 2018-03/txt/msg00454.txt.bz2 2018-03-19 14:17 GMT+01:00 Florian Weimer : > On 03/19/2018 02:11 PM, Andreas Schwab wrote: >> >> On M=C3=A4r 19 2018, Andrew Senkevich wro= te: >> >>> +static void >>> +do_test2 (void) >>> +{ >>> + uint32_t num =3D 0x20000000; >>> + uint32_t * large_buf; >>> + >>> + large_buf =3D mmap ((void*)0x70000000, num, PROT_READ | PROT_WRITE, >>> + MAP_PRIVATE | MAP_ANON | MAP_FIXED, -1, 0); >> >> Since you are using MAP_FIXED this may overwrite an existing mapping. > > > Leading to a hard-to-debug crash, maybe sporadically due to ASLR. Yes, I > have this concern as well. > > There was a long, long Linux thread about a non-overriding MAP_FIXED > variant, but as far as I can see, this has not been merged. Maybe it wou= ld > have helped here. > > Is it very difficult to split out this test into a separate test file? Th= en > link the whole thing statically, as non-PIE, and keep using MAP_FIXED. T= his > should make it quite likely that you don't override anything valuable. I think not very difficult, I will try this way. -- WBR, Andrew