1 files changed, 15 insertions, 3 deletions

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 67b9f035ba86..f86d1baa6302 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -616,12 +616,24 @@ xdr_shift_buf(struct xdr_buf *buf, size_t len)
 void xdr_init_encode(struct xdr_stream *xdr, struct xdr_buf *buf, uint32_t *p)
 {
         struct kvec *iov = buf->head;
+        int scratch_len = buf->buflen - buf->page_len - buf->tail[0].iov_len;
 
+        BUG_ON(scratch_len < 0);
         xdr->buf = buf;
         xdr->iov = iov;
-        xdr->end = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
-        buf->len = iov->iov_len = (char *)p - (char *)iov->iov_base;
-        xdr->p = p;
+        xdr->p = (uint32_t *)((char *)iov->iov_base + iov->iov_len);
+        xdr->end = (uint32_t *)((char *)iov->iov_base + scratch_len);
+        BUG_ON(iov->iov_len > scratch_len);
+
+        if (p != xdr->p && p != NULL) {
+                size_t len;
+
+                BUG_ON(p < xdr->p || p > xdr->end);
+                len = (char *)p - (char *)xdr->p;
+                xdr->p = p;
+                buf->len += len;
+                iov->iov_len += len;
+        }
 }
 EXPORT_SYMBOL(xdr_init_encode);