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_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 399F6C41604 for ; Sat, 3 Oct 2020 20:33:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E20D5206C1 for ; Sat, 3 Oct 2020 20:33:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Bp+Of4EY" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725946AbgJCUdX (ORCPT ); Sat, 3 Oct 2020 16:33:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49230 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725897AbgJCUdX (ORCPT ); Sat, 3 Oct 2020 16:33:23 -0400 Received: from mail-pf1-x442.google.com (mail-pf1-x442.google.com [IPv6:2607:f8b0:4864:20::442]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EF8DBC0613D0 for ; Sat, 3 Oct 2020 13:33:21 -0700 (PDT) Received: by mail-pf1-x442.google.com with SMTP id k8so3895931pfk.2 for ; Sat, 03 Oct 2020 13:33:21 -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=WfQ+i+BxpbFQx3pen9QNH4hEFsBqsYjP8pLH9bs7mUw=; b=Bp+Of4EY8R7dq7agpxR3FH4RsGGGxOLR03sus0ezi4ewM034U1nkstuEpOVj0UVGK7 6hxitcMpw5mM+Yfm8QmRVvQ2ih44rqmY7tM0a6O5kH6rq+4O1ht4+zHbFtpLfeX4qIeA z5vZtQkroTAmaYAlJrWPNNCQuQR73BWwS7ffYvVO56oo/BuBFW9sjwynLoi1Bnt9C8/c M3Eb1noqWQ62M6d528zW9GFdYwqdc6mqIJV7ckGNpVZiBzkHM6Wbh7v1xN8bN67c192N 3ds6niFo6VLc2jzfdQIqD+25jngBKhwtdPKRacTKVKcJyxWfX3Di23WJERmL75EPPTFQ togA== 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=WfQ+i+BxpbFQx3pen9QNH4hEFsBqsYjP8pLH9bs7mUw=; b=YCl0VxMB4SF/t1oFeiCqRN3ABKy7qUGcY5CQTn4IoYsYr+KxwC9N+xArLnQ+Ovzug+ v7cFPVKWHJKJUMVBIDMDKkmY1Qn42j+hRk7qrI7+S7Ad44O4OpqYqGW+3XXL5Vq3PgGF 87vdxGRm7HKnLcF/plB2CK5BzfiKJM/NrojEPiY/amj3swqn5p3jwGLGhsZTobv8Jo4S 0KXpQLH48uJ9ujaG4iKLm8O00LGTsXyLbX2dfsbcsw+bSDPXMuwv7jNZKlDaZkK0OfNl dlR1h6s4gnv/O+ElLvYCSCQhCrDs9HdBhwJA1CAtecPLJYov/VExZkAk0x0lk+bwZhxp RcIQ== X-Gm-Message-State: AOAM531FJAkiqjcyh0EZ9AI91sZm8DVDJghUQF4d4uRlHUwJrMpzrIii udNMcQzZgrF5qIfAjbVkebk= X-Google-Smtp-Source: ABdhPJzHEcb0FuV1DCvKntiRgzf3Bf7lfi0p9EM/K5/fze9qprL346jRWeiUX+qn8g9puKzep7Jqag== X-Received: by 2002:a62:3001:0:b029:142:2501:39e3 with SMTP id w1-20020a6230010000b0290142250139e3mr8528343pfw.50.1601757201024; Sat, 03 Oct 2020 13:33:21 -0700 (PDT) Received: from localhost.localdomain ([45.118.167.204]) by smtp.googlemail.com with ESMTPSA id v22sm5339736pff.159.2020.10.03.13.33.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 03 Oct 2020 13:33:20 -0700 (PDT) From: Anmol Karn To: dwmw2@infradead.org, richard@nod.at, viro@zeniv.linux.org.uk, sandeen@sandeen.net, dhowells@redhat.com Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, syzkaller-bugs@googlegroups.com, anmol.karan123@gmail.com, syzbot+9765367bb86a19d38732@syzkaller.appspotmail.com Subject: [Linux-kernel-mentees] [PATCH] fs: jffs2: super: Fix null pointer dereference in jffs2_parse_param() Date: Sun, 4 Oct 2020 02:03:10 +0530 Message-Id: <20201003203310.494524-1-anmol.karan123@gmail.com> X-Mailer: git-send-email 2.28.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org mtd is getting NULL dereferenced in jffs2_parse_param(), while checking condition for pool size when, case: opt is Opt_rp_size hits. - fs/jffs2/super.c The bug seems to get triggered in this line: if (opt > c->mtd->size) return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB", c->mtd->size / 1024); Fix this by adding a NULL check for 'c->mtd' device and return invalf(); which wraps errorf() and returns -EINVAL for convenience, which allows userspace to collect them directly. Reported-and-tested-by: syzbot+9765367bb86a19d38732@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=9765367bb86a19d38732 Signed-off-by: Anmol Karn --- fs/jffs2/super.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/jffs2/super.c b/fs/jffs2/super.c index 05d7878dfad1..f4ce67ac8486 100644 --- a/fs/jffs2/super.c +++ b/fs/jffs2/super.c @@ -203,6 +203,10 @@ static int jffs2_parse_param(struct fs_context *fc, struct fs_parameter *param) if (result.uint_32 > UINT_MAX / 1024) return invalf(fc, "jffs2: rp_size unrepresentable"); opt = result.uint_32 * 1024; + + if (!c->mtd) + return invalf(fc, "jffs2: mtd device is NULL"); + if (opt > c->mtd->size) return invalf(fc, "jffs2: Too large reserve pool specified, max is %llu KB", c->mtd->size / 1024); -- 2.28.0