SUNRPC: Don't decode beyond the end of the RPC reply message
Now that xdr_inline_decode() will automatically cross into the page buffers, we need to ensure that it doesn't exceed the total reply message length. This patch sets up a counter that tracks the number of words remaining in the reply message, and ensures that xdr_inline_decode, xdr_read_pages and xdr_enter_page respect the end of message boundary. Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
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@ -205,6 +205,7 @@ struct xdr_stream {
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struct kvec *iov; /* pointer to the current kvec */
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struct kvec scratch; /* Scratch buffer */
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struct page **page_ptr; /* pointer to the current page */
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unsigned int nwords; /* Remaining decode buffer length */
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};
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/*
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@ -630,12 +630,15 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p)
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xdr->buf = buf;
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xdr->scratch.iov_base = NULL;
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xdr->scratch.iov_len = 0;
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xdr->nwords = XDR_QUADLEN(buf->len);
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if (buf->head[0].iov_len != 0)
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xdr_set_iov(xdr, buf->head, buf->len);
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else if (buf->page_len != 0)
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xdr_set_page_base(xdr, 0, buf->len);
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if (p != NULL && p > xdr->p && xdr->end >= p)
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if (p != NULL && p > xdr->p && xdr->end >= p) {
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xdr->nwords -= p - xdr->p;
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xdr->p = p;
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}
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}
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EXPORT_SYMBOL_GPL(xdr_init_decode);
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@ -660,12 +663,14 @@ EXPORT_SYMBOL_GPL(xdr_init_decode_pages);
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static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)
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{
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unsigned int nwords = XDR_QUADLEN(nbytes);
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__be32 *p = xdr->p;
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__be32 *q = p + XDR_QUADLEN(nbytes);
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__be32 *q = p + nwords;
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if (unlikely(q > xdr->end || q < p))
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if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))
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return NULL;
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xdr->p = q;
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xdr->nwords -= nwords;
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return p;
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}
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@ -746,9 +751,16 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
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struct xdr_buf *buf = xdr->buf;
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struct kvec *iov;
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ssize_t shift;
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unsigned int nwords = XDR_QUADLEN(len);
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unsigned int end;
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int padding;
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if (xdr->nwords == 0)
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return;
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if (nwords > xdr->nwords) {
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nwords = xdr->nwords;
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len = nwords << 2;
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}
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/* Realign pages to current pointer position */
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iov = buf->head;
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shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
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@ -758,15 +770,15 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
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/* Truncate page data and move it into the tail */
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if (buf->page_len > len)
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xdr_shrink_pagelen(buf, buf->page_len - len);
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padding = (XDR_QUADLEN(len) << 2) - len;
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padding = (nwords << 2) - len;
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xdr->iov = iov = buf->tail;
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/* Compute remaining message length. */
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end = iov->iov_len;
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shift = buf->buflen - buf->len;
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if (shift < end)
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if (end > shift + padding)
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end -= shift;
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else if (shift > 0)
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end = 0;
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else
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end = padding;
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/*
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* Position current pointer at beginning of tail, and
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* set remaining message length.
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@ -774,6 +786,7 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len)
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xdr->p = (__be32 *)((char *)iov->iov_base + padding);
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xdr->end = (__be32 *)((char *)iov->iov_base + end);
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xdr->page_ptr = NULL;
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xdr->nwords = XDR_QUADLEN(end - padding);
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}
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EXPORT_SYMBOL_GPL(xdr_read_pages);
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@ -795,6 +808,7 @@ void xdr_enter_page(struct xdr_stream *xdr, unsigned int len)
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* set remaining message length.
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*/
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xdr_set_page_base(xdr, 0, len);
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xdr->nwords += XDR_QUADLEN(xdr->buf->page_len);
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}
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EXPORT_SYMBOL_GPL(xdr_enter_page);
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