nfs41: fix wrong error on callback header xdr overflow

Set NFS4ERR_RESOURCE as CB_COMPOUND status and do not return an op on
decode_op_hdr or encode_op_hdr buffer overflow.

NFS4ERR_RESOURCE is correct for v4.0. Will fix the return for v4.1 along with
all the other NFS4ERR_RESOURCE errors in a later patch.

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 18 insertions, 10 deletions

diff --git a/fs/nfs/callback_xdr.c b/fs/nfs/callback_xdr.c
index 8e1a2511c8be..6ae327871b86 100644
--- a/fs/nfs/callback_xdr.c
+++ b/fs/nfs/callback_xdr.c
@@ -28,6 +28,9 @@
 
 #define NFSDBG_FACILITY NFSDBG_CALLBACK
 
+/* Internal error code */
+#define NFS4ERR_RESOURCE_HDR    11050
+
 typedef __be32 (*callback_process_op_t)(void *, void *);
 typedef __be32 (*callback_decode_arg_t)(struct svc_rqst *, struct xdr_stream *, void *);
 typedef __be32 (*callback_encode_res_t)(struct svc_rqst *, struct xdr_stream *, void *);
@@ -173,7 +176,7 @@ static __be32 decode_op_hdr(struct xdr_stream *xdr, unsigned int *op)
         __be32 *p;
         p = read_buf(xdr, 4);
         if (unlikely(p == NULL))
-                return htonl(NFS4ERR_RESOURCE);
+                return htonl(NFS4ERR_RESOURCE_HDR);
         *op = ntohl(*p);
         return 0;
 }
@@ -465,7 +468,7 @@ static __be32 encode_op_hdr(struct xdr_stream *xdr, uint32_t op, __be32 res)
         
         p = xdr_reserve_space(xdr, 8);
         if (unlikely(p == NULL))
-                return htonl(NFS4ERR_RESOURCE);
+                return htonl(NFS4ERR_RESOURCE_HDR);
         *p++ = htonl(op);
         *p = res;
         return 0;
@@ -605,17 +608,15 @@ static __be32 process_op(uint32_t minorversion, int nop,
                 struct xdr_stream *xdr_out, void *resp)
 {
         struct callback_op *op = &callback_ops[0];
-        unsigned int op_nr = OP_CB_ILLEGAL;
+        unsigned int op_nr;
         __be32 status;
         long maxlen;
         __be32 res;
 
         dprintk("%s: start\n", __func__);
         status = decode_op_hdr(xdr_in, &op_nr);
-        if (unlikely(status)) {
-                status = htonl(NFS4ERR_OP_ILLEGAL);
-                goto out;
-        }
+        if (unlikely(status))
+                return status;
 
         dprintk("%s: minorversion=%d nop=%d op_nr=%u\n",
                 __func__, minorversion, nop, op_nr);
@@ -624,7 +625,7 @@ static __be32 process_op(uint32_t minorversion, int nop,
                                 preprocess_nfs4_op(op_nr, &op);
         if (status == htonl(NFS4ERR_OP_ILLEGAL))
                 op_nr = OP_CB_ILLEGAL;
-out:
+
         maxlen = xdr_out->end - xdr_out->p;
         if (maxlen > 0 && maxlen < PAGE_SIZE) {
                 if (likely(status == 0 && op->decode_args != NULL))
@@ -635,8 +636,8 @@ out:
                 status = htonl(NFS4ERR_RESOURCE);
 
         res = encode_op_hdr(xdr_out, op_nr, status);
-        if (status == 0)
-                status = res;
+        if (unlikely(res))
+                return res;
         if (op->encode_res != NULL && status == 0)
                 status = op->encode_res(rqstp, xdr_out, resp);
         dprintk("%s: done, status = %d\n", __func__, ntohl(status));
@@ -677,6 +678,13 @@ static __be32 nfs4_callback_compound(struct svc_rqst *rqstp, void *argp, void *r
                 nops++;
         }
 
+        /* Buffer overflow in decode_ops_hdr or encode_ops_hdr. Return
+        * resource error in cb_compound status without returning op */
+        if (unlikely(status == htonl(NFS4ERR_RESOURCE_HDR))) {
+                status = htonl(NFS4ERR_RESOURCE);
+                nops--;
+        }
+
         *hdr_res.status = status;
         *hdr_res.nops = htonl(nops);
         dprintk("%s: done, status = %u\n", __func__, ntohl(status));