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=-11.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,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 16350C43381 for ; Fri, 22 Mar 2019 12:37:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D9B82218A1 for ; Fri, 22 Mar 2019 12:37:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553258233; bh=vE5eD3VtBpLHYSKQEvLajtodux9ujApQCNOklDNKjFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=eqbO2OdVjaTTjhgZ+ZLJRXE6sbt8JdtGVOjPYjWouWy/pHYL4XLgD5SvF5pVEiZ6D q4Isli/gyr3TIfVWjN/pKiQcfzryaeHUQlZ3rvQZmwoCsHap01X64V2D861wY/NLuD +YpaI+nmOY8errFF0D/My2PUwBsbuhb+Fh9aFFeY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389191AbfCVMKV (ORCPT ); Fri, 22 Mar 2019 08:10:21 -0400 Received: from mail.kernel.org ([198.145.29.99]:48764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388767AbfCVMKU (ORCPT ); Fri, 22 Mar 2019 08:10:20 -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 5940B2082C; Fri, 22 Mar 2019 12:10:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553256619; bh=vE5eD3VtBpLHYSKQEvLajtodux9ujApQCNOklDNKjFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZgLymFztNr8Hn5+CxRBGB2+sL9cJRdcbD/npRHjT6KoeAeFL23Iv3jkgHHkDUzPJj dRzO8UoDGhZSO4BgTNLhX5epADSoGx8zBcHpujzDQIlJQ7SZBfeYzl0Y1esdMzVhE9 0DsyyuVFzdR9/WbkVYsHa8Jj3Zr6sGH4kU2cAnoY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, NeilBrown , "J. Bruce Fields" Subject: [PATCH 4.19 244/280] nfsd: fix memory corruption caused by readdir Date: Fri, 22 Mar 2019 12:16:37 +0100 Message-Id: <20190322111340.074557331@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111306.356185024@linuxfoundation.org> References: <20190322111306.356185024@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: NeilBrown commit b602345da6cbb135ba68cf042df8ec9a73da7981 upstream. If the result of an NFSv3 readdir{,plus} request results in the "offset" on one entry having to be split across 2 pages, and is sized so that the next directory entry doesn't fit in the requested size, then memory corruption can happen. When encode_entry() is called after encoding the last entry that fits, it notices that ->offset and ->offset1 are set, and so stores the offset value in the two pages as required. It clears ->offset1 but *does not* clear ->offset. Normally this omission doesn't matter as encode_entry_baggage() will be called, and will set ->offset to a suitable value (not on a page boundary). But in the case where cd->buflen < elen and nfserr_toosmall is returned, ->offset is not reset. This means that nfsd3proc_readdirplus will see ->offset with a value 4 bytes before the end of a page, and ->offset1 set to NULL. It will try to write 8bytes to ->offset. If we are lucky, the next page will be read-only, and the system will BUG: unable to handle kernel paging request at... If we are unlucky, some innocent page will have the first 4 bytes corrupted. nfsd3proc_readdir() doesn't even check for ->offset1, it just blindly writes 8 bytes to the offset wherever it is. Fix this by clearing ->offset after it is used, and copying the ->offset handling code from nfsd3_proc_readdirplus into nfsd3_proc_readdir. (Note that the commit hash in the Fixes tag is from the 'history' tree - this bug predates git). Fixes: 0b1d57cf7654 ("[PATCH] kNFSd: Fix nfs3 dentry encoding") Fixes-URL: https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=0b1d57cf7654 Cc: stable@vger.kernel.org (v2.6.12+) Signed-off-by: NeilBrown Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs3proc.c | 16 ++++++++++++++-- fs/nfsd/nfs3xdr.c | 1 + 2 files changed, 15 insertions(+), 2 deletions(-) --- a/fs/nfsd/nfs3proc.c +++ b/fs/nfsd/nfs3proc.c @@ -463,8 +463,19 @@ nfsd3_proc_readdir(struct svc_rqst *rqst &resp->common, nfs3svc_encode_entry); memcpy(resp->verf, argp->verf, 8); resp->count = resp->buffer - argp->buffer; - if (resp->offset) - xdr_encode_hyper(resp->offset, argp->cookie); + if (resp->offset) { + loff_t offset = argp->cookie; + + if (unlikely(resp->offset1)) { + /* we ended up with offset on a page boundary */ + *resp->offset = htonl(offset >> 32); + *resp->offset1 = htonl(offset & 0xffffffff); + resp->offset1 = NULL; + } else { + xdr_encode_hyper(resp->offset, offset); + } + resp->offset = NULL; + } RETURN_STATUS(nfserr); } @@ -533,6 +544,7 @@ nfsd3_proc_readdirplus(struct svc_rqst * } else { xdr_encode_hyper(resp->offset, offset); } + resp->offset = NULL; } RETURN_STATUS(nfserr); --- a/fs/nfsd/nfs3xdr.c +++ b/fs/nfsd/nfs3xdr.c @@ -921,6 +921,7 @@ encode_entry(struct readdir_cd *ccd, con } else { xdr_encode_hyper(cd->offset, offset64); } + cd->offset = NULL; } /*