1 files changed, 38 insertions, 10 deletions

diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 7e4bb0af24d7..43fb360784b7 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -369,7 +369,7 @@ int
 nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
 					struct nfsd3_writeargs *args)
 {
-	unsigned int len, v, hdr;
+	unsigned int len, v, hdr, dlen;
 	u32 max_blocksize = svc_max_payload(rqstp);
 
 	if (!(p = decode_fh(p, &args->fh))
@@ -379,18 +379,47 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
 	args->count = ntohl(*p++);
 	args->stable = ntohl(*p++);
 	len = args->len = ntohl(*p++);
+	/*
+	 * The count must equal the amount of data passed.
+	 */
+	if (args->count != args->len)
+		return 0;
 
+	/*
+	 * Check to make sure that we got the right number of
+	 * bytes.
+	 *
+	 * If more than one page was used, then compute the length
+	 * of the data in the request as the total size of the
+	 * request minus the transport protocol headers minus the
+	 * RPC protocol headers minus the NFS protocol fields
+	 * already consumed.  If the request fits into a single
+	 * page, then compete the length of the data as the size
+	 * of the NFS portion of the request minus the NFS
+	 * protocol fields already consumed.
+	 */
 	hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
-	if (rqstp->rq_arg.len < hdr ||
-	    rqstp->rq_arg.len - hdr < len)
+	if (rqstp->rq_respages != rqstp->rq_pages + 1) {
+		dlen = rqstp->rq_arg.len -
+			(PAGE_SIZE - rqstp->rq_arg.head[0].iov_len) - hdr;
+	} else {
+		dlen = rqstp->rq_arg.head[0].iov_len - hdr;
+	}
+	/*
+	 * Round the length of the data which was specified up to
+	 * the next multiple of XDR units and then compare that
+	 * against the length which was actually received.
+	 */
+	if (dlen != ((len + 3) & ~0x3))
 		return 0;
 
+	if (args->count > max_blocksize) {
+		args->count = max_blocksize;
+		len = args->len = max_blocksize;
+	}
 	rqstp->rq_vec[0].iov_base = (void*)p;
 	rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
-
-	if (len > max_blocksize)
-		len = max_blocksize;
-	v=  0;
+	v = 0;
 	while (len > rqstp->rq_vec[v].iov_len) {
 		len -= rqstp->rq_vec[v].iov_len;
 		v++;
@@ -398,9 +427,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
 		rqstp->rq_vec[v].iov_len = PAGE_SIZE;
 	}
 	rqstp->rq_vec[v].iov_len = len;
-	args->vlen = v+1;
-
-	return args->count == args->len && rqstp->rq_vec[0].iov_len > 0;
+	args->vlen = v + 1;
+	return 1;
 }
 
 int