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