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Subject[PATCH 4.9 69/83] sunrpc: correct the computation for page_ptr when truncating
4.9-stable review patch.  If anyone has any objections, please let me know.


From: Frank Sorenson <>

commit 5d7a5bcb67c70cbc904057ef52d3fcfeb24420bb upstream.

When truncating the encode buffer, the page_ptr is getting
advanced, causing the next page to be skipped while encoding.
The page is still included in the response, so the response
contains a page of bogus data.

We need to adjust the page_ptr backwards to ensure we encode
the next page into the correct place.

We saw this triggered when concurrent directory modifications caused
nfsd4_encode_direct_fattr() to return nfserr_noent, and the resulting
call to xdr_truncate_encode() corrupted the READDIR reply.

Signed-off-by: Frank Sorenson <>
Signed-off-by: J. Bruce Fields <>
Signed-off-by: Greg Kroah-Hartman <>

net/sunrpc/xdr.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)

--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -639,11 +639,10 @@ void xdr_truncate_encode(struct xdr_stre
- if (fraglen) {
+ if (fraglen)
xdr->end = head->iov_base + head->iov_len;
- xdr->page_ptr--;
- }
/* (otherwise assume xdr->end is already set) */
+ xdr->page_ptr--;
head->iov_len = len;
buf->len = len;
xdr->p = head->iov_base + head->iov_len;

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