The NFSv2/NFSv3 server does not handle zero length WRITE requests correctly

[safe/jmp/linux-2.6] / fs / nfsd / nfsxdr.c

diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 0c24b9e..6035e03 100644 (file)
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -284,8 +284,9 @@ int
 nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
                                        struct nfsd_writeargs *args)
 {
-       unsigned int len;
+       unsigned int len, hdr, dlen;
        int v;
+
        if (!(p = decode_fh(p, &args->fh)))
                return 0;
 
@@ -293,11 +294,42 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
        args->offset = ntohl(*p++);     /* offset */
        p++;                            /* totalcount */
        len = args->len = ntohl(*p++);
-       rqstp->rq_vec[0].iov_base = (void*)p;
-       rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len -
-                               (((void*)p) - rqstp->rq_arg.head[0].iov_base);
+       /*
+        * The protocol specifies a maximum of 8192 bytes.
+        */
        if (len > NFSSVC_MAXBLKSIZE_V2)
-               len = NFSSVC_MAXBLKSIZE_V2;
+               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_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;
+
+       rqstp->rq_vec[0].iov_base = (void*)p;
+       rqstp->rq_vec[0].iov_len = rqstp->rq_arg.head[0].iov_len - hdr;
        v = 0;
        while (len > rqstp->rq_vec[v].iov_len) {
                len -= rqstp->rq_vec[v].iov_len;
@@ -306,8 +338,8 @@ nfssvc_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 rqstp->rq_vec[0].iov_len > 0;
+       args->vlen = v + 1;
+       return 1;
 }
 
 int