Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752568AbdFAPus (ORCPT ); Thu, 1 Jun 2017 11:50:48 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33922 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751432AbdFAPpV (ORCPT ); Thu, 1 Jun 2017 11:45:21 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Ari Kauppi" , "NeilBrown" , "Tuomas =?UTF-8?Q?Haanp=C3=A4=C3=A4?=" , "J. Bruce Fields" Date: Thu, 01 Jun 2017 16:43:16 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.16 204/212] nfsd: stricter decoding of write-like NFSv2/v3 ops In-Reply-To: X-SA-Exim-Connect-IP: 82.70.136.246 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1762 Lines: 55 3.16.44-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: "J. Bruce Fields" commit 13bf9fbff0e5e099e2b6f003a0ab8ae145436309 upstream. The NFSv2/v3 code does not systematically check whether we decode past the end of the buffer. This generally appears to be harmless, but there are a few places where we do arithmetic on the pointers involved and don't account for the possibility that a length could be negative. Add checks to catch these. Reported-by: Tuomas Haanpää Reported-by: Ari Kauppi Reviewed-by: NeilBrown Signed-off-by: J. Bruce Fields Signed-off-by: Ben Hutchings --- fs/nfsd/nfs3xdr.c | 4 ++++ fs/nfsd/nfsxdr.c | 2 ++ 2 files changed, 6 insertions(+) --- a/fs/nfsd/nfs3xdr.c +++ b/fs/nfsd/nfs3xdr.c @@ -373,6 +373,8 @@ nfs3svc_decode_writeargs(struct svc_rqst args->count = ntohl(*p++); args->stable = ntohl(*p++); len = args->len = ntohl(*p++); + if ((void *)p > head->iov_base + head->iov_len) + return 0; /* * The count must equal the amount of data passed. */ @@ -476,6 +478,8 @@ nfs3svc_decode_symlinkargs(struct svc_rq /* first copy and check from the first page */ old = (char*)p; vec = &rqstp->rq_arg.head[0]; + if ((void *)old > vec->iov_base + vec->iov_len) + return 0; avail = vec->iov_len - (old - (char*)vec->iov_base); while (len && avail && *old) { *new++ = *old++; --- a/fs/nfsd/nfsxdr.c +++ b/fs/nfsd/nfsxdr.c @@ -303,6 +303,8 @@ nfssvc_decode_writeargs(struct svc_rqst * bytes. */ hdr = (void*)p - head->iov_base; + if (hdr > head->iov_len) + return 0; dlen = head->iov_len + rqstp->rq_arg.page_len - hdr; /*