From 13bf9fbff0e5e099e2b6f003a0ab8ae145436309 Mon Sep 17 00:00:00 2001 From: "J. Bruce Fields" Date: Fri, 21 Apr 2017 15:26:30 -0400 Subject: [PATCH] nfsd: stricter decoding of write-like NFSv2/v3 ops MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields --- fs/nfsd/nfs3xdr.c | 4 ++++ fs/nfsd/nfsxdr.c | 2 ++ 2 files changed, 6 insertions(+) diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c index d18cfddbe115..452334694a5d 100644 --- a/fs/nfsd/nfs3xdr.c +++ b/fs/nfsd/nfs3xdr.c @@ -369,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p, 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. */ @@ -472,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p, /* 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++; diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c index 59bd88a23a3d..de07ff625777 100644 --- a/fs/nfsd/nfsxdr.c +++ b/fs/nfsd/nfsxdr.c @@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p, * bytes. */ hdr = (void*)p - head->iov_base; + if (hdr > head->iov_len) + return 0; dlen = head->iov_len + rqstp->rq_arg.page_len - hdr; /* -- 2.20.1