Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754563AbdH1IQ2 (ORCPT ); Mon, 28 Aug 2017 04:16:28 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:35244 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754064AbdH1IQZ (ORCPT ); Mon, 28 Aug 2017 04:16:25 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chuck Lever , "J. Bruce Fields" Subject: [PATCH 3.18 15/22] nfsd: Limit end of page list when decoding NFSv4 WRITE Date: Mon, 28 Aug 2017 10:05:59 +0200 Message-Id: <20170828080454.412653260@linuxfoundation.org> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20170828080453.804109196@linuxfoundation.org> References: <20170828080453.804109196@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1609 Lines: 48 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chuck Lever commit fc788f64f1f3eb31e87d4f53bcf1ab76590d5838 upstream. When processing an NFSv4 WRITE operation, argp->end should never point past the end of the data in the final page of the page list. Otherwise, nfsd4_decode_compound can walk into uninitialized memory. More critical, nfsd4_decode_write is failing to increment argp->pagelen when it increments argp->pagelist. This can cause later xdr decoders to assume more data is available than really is, which can cause server crashes on malformed requests. Signed-off-by: Chuck Lever Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- fs/nfsd/nfs4xdr.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) --- a/fs/nfsd/nfs4xdr.c +++ b/fs/nfsd/nfs4xdr.c @@ -127,7 +127,7 @@ static void next_decode_page(struct nfsd argp->p = page_address(argp->pagelist[0]); argp->pagelist++; if (argp->pagelen < PAGE_SIZE) { - argp->end = argp->p + (argp->pagelen>>2); + argp->end = argp->p + XDR_QUADLEN(argp->pagelen); argp->pagelen = 0; } else { argp->end = argp->p + (PAGE_SIZE>>2); @@ -1235,9 +1235,7 @@ nfsd4_decode_write(struct nfsd4_compound argp->pagelen -= pages * PAGE_SIZE; len -= pages * PAGE_SIZE; - argp->p = (__be32 *)page_address(argp->pagelist[0]); - argp->pagelist++; - argp->end = argp->p + XDR_QUADLEN(PAGE_SIZE); + next_decode_page(argp); } argp->p += XDR_QUADLEN(len);