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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 D4920C48BDF for ; Tue, 15 Jun 2021 16:27:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF6B1617ED for ; Tue, 15 Jun 2021 16:27:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231282AbhFOQ3Y (ORCPT ); Tue, 15 Jun 2021 12:29:24 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231251AbhFOQ3M (ORCPT ); Tue, 15 Jun 2021 12:29:12 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E0EF6C06175F; Tue, 15 Jun 2021 09:27:06 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id 13-20020a17090a08cdb029016eed209ca4so1834657pjn.1; Tue, 15 Jun 2021 09:27:06 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=FdF3wW4T8FRZFucBIyQHf3j+zRm6LsxIJwnfUlfK+Q4=; b=OzI5w5V9+U2EOmeDiAei3lguVsnZxNuFNK164+UsTHn673OW2iaoBqRCbOZ+Zsne0l U8uDmBt8sRHl0BEu2RcfG7nD/CvZ2VUOigpBJzVK6mstyTlqKId2s2ft0heudEeuSws2 G2ZRj3CrZNde2QflwyfNjtdiC43ASssVU1+1V5ZEnChGGYUA0pciQVuwydrrTrDrOpJF K4oiekfV/rpRXRs9qGcHEbt6/528rWLOLcJoFyjlf60FTSphvoxo4n54pNb3Gjdpeqxq bICXVAd6BwHq/dPEDVRtREBg4ppfFmkHtWWa3qH1dSnawcaex3PZ+f0GgXpkH/R90C8N QqwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=FdF3wW4T8FRZFucBIyQHf3j+zRm6LsxIJwnfUlfK+Q4=; b=K641ZgOsoa0Z0CQDYA+MyMhv6rhyUb1ugZHzssZf+4jJFIi7UjvCPmi+ShrtWSmKCm 9Z+8yQst9AZy4HZW/6VJyTRSBCKEZXo10UNg4ImGZZJAyNU0sJR+moZ32gZHgH1/El0J LgDIa4yViiuj+e+AuiP+iGfRbZFrfggO602iKm38pnF80lYX5xQRlgQhBD8sZG+ATppu kYXHxtq8k4SaaCrLkczJQsntHi9hafEz1kZ5S/CSvGxu6Hh4G0lkivvZXfN2ufi74Ona 78FS9hXUDiR+Up4VFZb5CjTsomC/xc010UTOkq5AZR1OiBZueBisgTgDa0t5+QnOkarM 3L3Q== X-Gm-Message-State: AOAM530SNxpp5fkuljg7wrwGMsYvJVdgc8EpAhxoeuwoHvj+MIGT4BfE O8H6ZJTBKfxxdUUJdqC07BE= X-Google-Smtp-Source: ABdhPJyL1Yi60ltBMEkgVksv87fRWnLmIxRHdG2+l3q0RuiL9fcDc7tchujOwwSo37QnDMS69zk6HA== X-Received: by 2002:a17:902:b497:b029:115:e287:7b55 with SMTP id y23-20020a170902b497b0290115e2877b55mr4804360plr.79.1623774426347; Tue, 15 Jun 2021 09:27:06 -0700 (PDT) Received: from laptop.hsd1.wa.comcast.net ([2601:600:8500:5f14:d627:c51e:516e:a105]) by smtp.gmail.com with ESMTPSA id c25sm15535858pfo.130.2021.06.15.09.27.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Jun 2021 09:27:05 -0700 (PDT) From: Andrei Vagin To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, Kees Cook , linux-fsdevel@vger.kernel.org, Andrei Vagin Subject: [PATCH] exec/binfmt_script: trip zero bytes from the buffer Date: Tue, 15 Jun 2021 09:23:46 -0700 Message-Id: <20210615162346.16032-1-avagin@gmail.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Without this fix, if we try to run a script that contains only the interpreter line, the interpreter is executed with one extra empty argument. The code is written so that i_end has to be set to the end of valuable data in the buffer. Fixes: ccbb18b67323 ("exec/binfmt_script: Don't modify bprm->buf and then return -ENOEXEC") Cc: "Eric W. Biederman" Signed-off-by: Andrei Vagin --- fs/binfmt_script.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/binfmt_script.c b/fs/binfmt_script.c index 1b6625e95958..e242680f96e1 100644 --- a/fs/binfmt_script.c +++ b/fs/binfmt_script.c @@ -68,6 +68,9 @@ static int load_script(struct linux_binprm *bprm) if (!next_terminator(i_end, buf_end)) return -ENOEXEC; i_end = buf_end; + /* Trim zero bytes from i_end */ + while (i_end[-1] == 0) + i_end--; } /* Trim any trailing spaces/tabs from i_end */ while (spacetab(i_end[-1])) -- 2.31.1