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SUNRPC: Don't decode beyond the end of the RPC reply message

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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>
This commit is contained in:
Trond Myklebust 2012-06-20 09:58:35 -04:00
parent 1537693cea
commit bfeea1dc1c
2 changed files with 22 additions and 7 deletions
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1
include/linux/sunrpc/xdr.h
View File

@ -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 */
};
/*

28
net/sunrpc/xdr.c
View File

@ -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);