Commit bfeea1dc authored by Trond Myklebust's avatar Trond Myklebust
Browse files

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: default avatarTrond Myklebust <Trond.Myklebust@netapp.com>
parent 1537693c

include/linux/sunrpc/xdr.h

+1 −0
Original line number Diff line number Diff line
@@ -205,6 +205,7 @@ struct xdr_stream { 
	struct kvec *iov;	/* pointer to the current kvec */

	struct kvec scratch;	/* Scratch buffer */

	struct page **page_ptr;	/* pointer to the current page */

	unsigned int nwords;	/* Remaining decode buffer length */

};



/*

net/sunrpc/xdr.c

+21 −7
Original line number Diff line number Diff line
@@ -630,13 +630,16 @@ void xdr_init_decode(struct xdr_stream *xdr, struct xdr_buf *buf, __be32 *p) 
	xdr->buf = buf;

	xdr->scratch.iov_base = NULL;

	xdr->scratch.iov_len = 0;

	xdr->nwords = XDR_QUADLEN(buf->len);

	if (buf->head[0].iov_len != 0)

		xdr_set_iov(xdr, buf->head, buf->len);

	else if (buf->page_len != 0)

		xdr_set_page_base(xdr, 0, buf->len);

	if (p != NULL && p > xdr->p && xdr->end >= p)

	if (p != NULL && p > xdr->p && xdr->end >= p) {

		xdr->nwords -= p - xdr->p;

		xdr->p = p;

	}

}

EXPORT_SYMBOL_GPL(xdr_init_decode);



/**
@@ -660,12 +663,14 @@ EXPORT_SYMBOL_GPL(xdr_init_decode_pages); 


static __be32 * __xdr_inline_decode(struct xdr_stream *xdr, size_t nbytes)

{

	unsigned int nwords = XDR_QUADLEN(nbytes);

	__be32 *p = xdr->p;

	__be32 *q = p + XDR_QUADLEN(nbytes);

	__be32 *q = p + nwords;



	if (unlikely(q > xdr->end || q < p))

	if (unlikely(nwords > xdr->nwords || q > xdr->end || q < p))

		return NULL;

	xdr->p = q;

	xdr->nwords -= nwords;

	return p;

}
@@ -746,9 +751,16 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len) 
	struct xdr_buf *buf = xdr->buf;

	struct kvec *iov;

	ssize_t shift;

	unsigned int nwords = XDR_QUADLEN(len);

	unsigned int end;

	int padding;



	if (xdr->nwords == 0)

		return;

	if (nwords > xdr->nwords) {

		nwords = xdr->nwords;

		len = nwords << 2;

	}

	/* Realign pages to current pointer position */

	iov  = buf->head;

	shift = iov->iov_len + (char *)iov->iov_base - (char *)xdr->p;
@@ -758,15 +770,15 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len) 
	/* Truncate page data and move it into the tail */

	if (buf->page_len > len)

		xdr_shrink_pagelen(buf, buf->page_len - len);

	padding = (XDR_QUADLEN(len) << 2) - len;

	padding = (nwords << 2) - len;

	xdr->iov = iov = buf->tail;

	/* Compute remaining message length.  */

	end = iov->iov_len;

	shift = buf->buflen - buf->len;

	if (shift < end)

	if (end > shift + padding)

		end -= shift;

	else if (shift > 0)

		end = 0;

	else

		end = padding;

	/*

	 * Position current pointer at beginning of tail, and

	 * set remaining message length.
@@ -774,6 +786,7 @@ void xdr_read_pages(struct xdr_stream *xdr, unsigned int len) 
	xdr->p = (__be32 *)((char *)iov->iov_base + padding);

	xdr->end = (__be32 *)((char *)iov->iov_base + end);

	xdr->page_ptr = NULL;

	xdr->nwords = XDR_QUADLEN(end - padding);

}

EXPORT_SYMBOL_GPL(xdr_read_pages);
@@ -795,6 +808,7 @@ void xdr_enter_page(struct xdr_stream *xdr, unsigned int len) 
	 * set remaining message length.

	 */

	xdr_set_page_base(xdr, 0, len);

	xdr->nwords += XDR_QUADLEN(xdr->buf->page_len);

}

EXPORT_SYMBOL_GPL(xdr_enter_page);

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