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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 5161AC433E0 for ; Tue, 16 Jun 2020 16:07:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F7B2208D5 for ; Tue, 16 Jun 2020 16:07:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592323679; bh=JMlBOiZ+vCeIqMWFevpV9y3+A1JmqSlgaldOXzG2dsY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ruwqXAbUgR+FzwiFUtKVf79JJ+fAU94WXccnmrHa+3BgmV83pLN0aEjZFPLXyhcUR 36/1ha0W+ngKGKfxWX/oYJ1+dM9t1OdS3Osew+KDf/zikCCUx/QQyaNvQglYsKFAAy XfucDLujxjK5gBlhlOT/b4pFrUWKRj/mtsIYP76w= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732493AbgFPQH5 (ORCPT ); Tue, 16 Jun 2020 12:07:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:38924 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732216AbgFPPqh (ORCPT ); Tue, 16 Jun 2020 11:46:37 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 5538820776; Tue, 16 Jun 2020 15:46:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592322396; bh=JMlBOiZ+vCeIqMWFevpV9y3+A1JmqSlgaldOXzG2dsY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vf6xSHM577ciPFz67LuUyGpHOgD2jqicayJix/gx+rNBnIV9B2yu100VYaW+8olaF dwFCV5dZjq+7yOgQKUdDec5+1Yn5o2TwafY5/0IR+MUXxzQTxjwzL248xgqGrnmG9T F65tLOGTQJJ5vU688w7Sh4+d8/niEKNhQWjsB5Gs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Amir Goldstein , Miklos Szeredi , syzbot+61958888b1c60361a791@syzkaller.appspotmail.com Subject: [PATCH 5.7 115/163] ovl: fix out of bounds access warning in ovl_check_fb_len() Date: Tue, 16 Jun 2020 17:34:49 +0200 Message-Id: <20200616153112.311331992@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200616153106.849127260@linuxfoundation.org> References: <20200616153106.849127260@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Amir Goldstein commit 522f6e6cba6880a038e2bd88e10390b84cd3febd upstream. syzbot reported out of bounds memory access from open_by_handle_at() with a crafted file handle that looks like this: { .handle_bytes = 2, .handle_type = OVL_FILEID_V1 } handle_bytes gets rounded down to 0 and we end up calling: ovl_check_fh_len(fh, 0) => ovl_check_fb_len(fh + 3, -3) But fh buffer is only 2 bytes long, so accessing struct ovl_fb at fh + 3 is illegal. Fixes: cbe7fba8edfc ("ovl: make sure that real fid is 32bit aligned in memory") Reported-and-tested-by: syzbot+61958888b1c60361a791@syzkaller.appspotmail.com Cc: # v5.5 Signed-off-by: Amir Goldstein Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/overlayfs/overlayfs.h | 3 +++ 1 file changed, 3 insertions(+) --- a/fs/overlayfs/overlayfs.h +++ b/fs/overlayfs/overlayfs.h @@ -355,6 +355,9 @@ int ovl_check_fb_len(struct ovl_fb *fb, static inline int ovl_check_fh_len(struct ovl_fh *fh, int fh_len) { + if (fh_len < sizeof(struct ovl_fh)) + return -EINVAL; + return ovl_check_fb_len(&fh->fb, fh_len - OVL_FH_WIRE_OFFSET); }