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=-12.8 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 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 C7EB5C07E99 for ; Mon, 5 Jul 2021 18:35:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 995F3613AE for ; Mon, 5 Jul 2021 18:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229829AbhGESib (ORCPT ); Mon, 5 Jul 2021 14:38:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51026 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229757AbhGESia (ORCPT ); Mon, 5 Jul 2021 14:38:30 -0400 Received: from mail-wm1-x341.google.com (mail-wm1-x341.google.com [IPv6:2a00:1450:4864:20::341]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FC5CC061574 for ; Mon, 5 Jul 2021 11:35:52 -0700 (PDT) Received: by mail-wm1-x341.google.com with SMTP id u8-20020a7bcb080000b02901e44e9caa2aso548420wmj.4 for ; Mon, 05 Jul 2021 11:35:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:mime-version:content-disposition; bh=i11aeIbYZIAXnmIV6Qy6K11j95TILIFNwLQ1SkwuXdE=; b=oehPW+i41sCkTm3lhw6YKRzMAD5vJfWof6uNlQAvObsiCn0V6x2h66HbmN9eonTpYJ tdSwE8ViQEzS2WQRImJ3bmEO+5AeuF2V4SSHhKOYvNLAyI6oPqERWY00GB99xCuKCV94 a7UYdu8yB/bLSBf6cjUGU2i7H7l2AxBsB/VPeEfJ3UWfgz22fc8FgZVG4qTdAMoqqFVP uXoCDMkKTJ49THDmiLkt0DHvlClmtCPOBSgh/EHQR6OX/pos6yXeagnU7D5voeN9e0hn c2kSKUWrboOUd3HU5/TDAklHgH6LRRqVAK28wCHdkL/Friblxgt0zP45F5yTcqhUe11/ hm8A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:mime-version :content-disposition; bh=i11aeIbYZIAXnmIV6Qy6K11j95TILIFNwLQ1SkwuXdE=; b=otxqgfAsxNn+7f/XoN0o2/OcL03yrCAU8eqja3K/esmwZYBscjDEMNDDyOCTkVq6OM LAi8TYkwK80FV4m5UpyEk7wWBtndwKl935Jbp13DIaG5L6jpc3zDo1AOBjhdsWrlRS6g z/Obw234e/bpW6qJu/e1tCXY7rf8te7i5aqk8a7jEI/U9JJ4IaNAnypC5mIDY30VffCi +zUGNe+HxEsKufUyw3uHKKYVpLZu6Za+wYHco+zLz1XJvnFILNt2bxPu1Tnh5+EAo2Qu W2hEy6dqyLFU9G7+6HSfEDyfA6DOhzQbLXnd2zGDNx66KP6Puq7xmDvlafqU2ht6Z898 ZArg== X-Gm-Message-State: AOAM533qB5Ngc68UpbiplbFxlXVF/OJTgNhlubxYsVCqLldStKErI3Vf rHRBhhJTpTJFekZPLcn5mms= X-Google-Smtp-Source: ABdhPJws6OGNV7wUNJLAjVEbgsr0uK708PgUyRKI0cz5IAH5U7efGUeoWBhtAGGHAl8ONGy5xhE/jA== X-Received: by 2002:a7b:c417:: with SMTP id k23mr422350wmi.87.1625510151283; Mon, 05 Jul 2021 11:35:51 -0700 (PDT) Received: from itaypc ([77.124.41.135]) by smtp.gmail.com with ESMTPSA id p9sm13723699wrx.59.2021.07.05.11.35.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 05 Jul 2021 11:35:50 -0700 (PDT) Date: Mon, 5 Jul 2021 21:35:34 +0300 From: Itay Ie To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org Subject: [PATCH] fs/binfmt_elf: disallow e_phnum that equals zero Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The elf_ex.e_phnum field can be set to zero. If elf_ex.e_phnum is set to zero, then a redundant kmalloc with the size zero is called and a following kfree. Check if elf_ex.e_phnum equals zero, and prevent the redundant kmalloc and kfree. Signed-off-by: Itay Ie --- fs/binfmt_elf.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/binfmt_elf.c b/fs/binfmt_elf.c index 187b3f2b9202..f25e8f241ae9 100644 --- a/fs/binfmt_elf.c +++ b/fs/binfmt_elf.c @@ -1348,7 +1348,8 @@ static int load_elf_library(struct file *file) /* First of all, some simple consistency checks */ if (elf_ex.e_type != ET_EXEC || elf_ex.e_phnum > 2 || - !elf_check_arch(&elf_ex) || !file->f_op->mmap) + elf_ex.e_phnum == 0 || !elf_check_arch(&elf_ex) || + !file->f_op->mmap) goto out; if (elf_check_fdpic(&elf_ex)) goto out; @@ -1356,7 +1357,7 @@ static int load_elf_library(struct file *file) /* Now read in all of the header information */ j = sizeof(struct elf_phdr) * elf_ex.e_phnum; - /* j < ELF_MIN_ALIGN because elf_ex.e_phnum <= 2 */ + /* j < ELF_MIN_ALIGN because elf_ex.e_phnum is 1 or 2 */ error = -ENOMEM; elf_phdata = kmalloc(j, GFP_KERNEL); -- 2.32.0