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=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, URIBL_BLOCKED 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 07B49C6778A for ; Thu, 5 Jul 2018 15:44:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B151C23FF6 for ; Thu, 5 Jul 2018 15:44:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=google.com header.i=@google.com header.b="wAzQyIqS"; dkim=fail reason="signature verification failed" (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="TxD3Se36" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B151C23FF6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753924AbeGEPoa (ORCPT ); Thu, 5 Jul 2018 11:44:30 -0400 Received: from mail-yw0-f196.google.com ([209.85.161.196]:46801 "EHLO mail-yw0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753534AbeGEPoT (ORCPT ); Thu, 5 Jul 2018 11:44:19 -0400 Received: by mail-yw0-f196.google.com with SMTP id e23-v6so2601150ywe.13 for ; Thu, 05 Jul 2018 08:44:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=WB00rg/X7o98XNa0SYG7GN650VkRI0jQvvn8re5I+jM=; b=wAzQyIqSK77VEDTUSyhn4lhaNS2X41UZDUgEO3A+okKQImboB+FXsC7IoP2f8B6rq5 jRj2+WXm2gl2KAasnAV9Z8ZqOIKli314mzXhODLDcMa/qwEtofHFtJmor0MGVG267flR lu5dyoChZHKU8bxK1U3YOtJoqRn92QpVNKK7Xxfbbh+CaaEne5ss7ViS1Ry0K3FJNRsZ w8BAqmmSFVlxwMy3SdTNs3mGdNJx1OZQaBjoT58XIvXCpTvKgm5Jl8dhsU2c7qAVC4h5 Qc4Ow7ejNA3GGAVwV7/CPPVqk7HInGsiGbs7sGnnCyXL9t4hqETBrDW+dbMGXPQNttXn aWEA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=WB00rg/X7o98XNa0SYG7GN650VkRI0jQvvn8re5I+jM=; b=TxD3Se36ttkEC89IbIht7zet4FkJ1lBZpstwvr3ijtpn/KnWM2mWNiHxZjal1797rW RDvgYyQcAvRJTugNWyMkw1zUrFevY8yqtCKf4GoAHwl6nJ1NYUkyCJ8vvGbTf0kgBs6y LLrfOVexKvWtNdVgwnymjPvGb9Zz0JImZh1Rk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=WB00rg/X7o98XNa0SYG7GN650VkRI0jQvvn8re5I+jM=; b=NY/6t3XeXDkL6TRPdmXPtDUlG/J7KnGHQmr23+tXQh56B33QW1+XSBFjFkTf3irwSP FC0HRftrVUlPmpz9oQ8TkcF24+ayjV89r6WEQ92bayDQQzCRBFAqJkPyvNdevVwtXEA+ aQSV/K2T1fIPaaAZwCuZzsLzHNt5JS3BYte3rrZvH8DULBPcEW0Ua07rQ946ZdzyWCPN haYcj03iUS1rGPKjML1f82eVHkZ6Sc5f0UjtuiVf5yPwWiJFtYAmu1EjqrnBcC6B5fGh IYmcFIiz5jmkB5KHcZvP/8kPWIdAUoqk7mM0M1/wGeIw8HeKfHuTQuOF5gC8bwhaUrjj xdCA== X-Gm-Message-State: APt69E2PKTa4fHOre9lpSFE+hh/X77tD32vH8llC4VvXEVnMmOJ0J120 6O8U4gRhKPj2IUE9F9fAWzqrXtGWw0s1by9Gum/QdND8 X-Google-Smtp-Source: AAOMgpc5Zcngj4LnYNSBQ8FoqmieiRqzPyc1X1EzDf3pEIKMIWyqIOxpNg8s3hdn/IyoBUStqD2PGPuaqBn0qL7n9Uo= X-Received: by 2002:a0d:fa42:: with SMTP id k63-v6mr803852ywf.53.1530805458798; Thu, 05 Jul 2018 08:44:18 -0700 (PDT) MIME-Version: 1.0 Received: by 2002:a25:5f51:0:0:0:0:0 with HTTP; Thu, 5 Jul 2018 08:44:18 -0700 (PDT) In-Reply-To: <20180705145539.9627-1-osalvador@techadventures.net> References: <20180705145539.9627-1-osalvador@techadventures.net> From: Kees Cook Date: Thu, 5 Jul 2018 08:44:18 -0700 X-Google-Sender-Auth: ol1tudMQ7VeuWZd23e-oGV4NV3U Message-ID: Subject: Re: [PATCH] fs, elf: Make sure to page align bss in load_elf_library To: osalvador@techadventures.net Cc: "linux-fsdevel@vger.kernel.org" , Linux-MM , LKML , Michal Hocko , Tetsuo Handa , Nicolas Pitre , Oscar Salvador 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, Jul 5, 2018 at 7:55 AM, wrote: > From: Oscar Salvador > > The current code does not make sure to page align bss before calling > vm_brk(), and this can lead to a VM_BUG_ON() in __mm_populate() > due to the requested lenght not being correctly aligned. > > Let us make sure to align it properly. > > Signed-off-by: Oscar Salvador > Tested-by: Tetsuo Handa > Reported-by: syzbot+5dcb560fe12aa5091c06@syzkaller.appspotmail.com Wow. CONFIG_USELIB? I'm surprised distros are still using this. 32-bit only, and libc5 and earlier only. Regardless, this appears to match the current bss alignment logic in the main elf loader, so: Acked-by: Kees Cook -Kees > --- > fs/binfmt_elf.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c > index 0ac456b52bdd..816cc921cf36 100644 > --- a/fs/binfmt_elf.c > +++ b/fs/binfmt_elf.c > @@ -1259,9 +1259,8 @@ static int load_elf_library(struct file *file) > goto out_free_ph; > } > > - len = ELF_PAGESTART(eppnt->p_filesz + eppnt->p_vaddr + > - ELF_MIN_ALIGN - 1); > - bss = eppnt->p_memsz + eppnt->p_vaddr; > + len = ELF_PAGEALIGN(eppnt->p_filesz + eppnt->p_vaddr); > + bss = ELF_PAGEALIGN(eppnt->p_memsz + eppnt->p_vaddr); > if (bss > len) { > error = vm_brk(len, bss - len); > if (error) > -- > 2.13.6 > -- Kees Cook Pixel Security