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>
diff --git a/include/linux/sunrpc/xdr.h b/include/linux/sunrpc/xdr.h
index af70af3..f1e7f88 100644
--- a/include/linux/sunrpc/xdr.h
+++ b/include/linux/sunrpc/xdr.h
@@ -205,6 +205,7 @@
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 */
};
/*
diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 21d041c..5643feb 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -630,12 +630,15 @@
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 @@
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 @@
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 @@
/* 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 @@
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 @@
* 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);