DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C7B852080A
From:   Frank Sorenson <sorenson@redhat.com>
To:     bfields@fieldses.org
Cc:     linux-nfs@vger.kernel.org, jlayton@kernel.org
Subject: [PATCH] sunrpc: correct the computation for page_ptr when truncating
Date:   Tue, 30 Oct 2018 15:10:40 -0500
Message-Id: <20181030201040.2024882-1-sorenson@redhat.com>
Sender: linux-nfs-owner@vger.kernel.org
Precedence: bulk

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.

Signed-off-by: Frank Sorenson <sorenson@redhat.com>
---
 net/sunrpc/xdr.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c
index 2bbb8d38d2bf..5cfb9e0a18dc 100644
--- a/net/sunrpc/xdr.c
+++ b/net/sunrpc/xdr.c
@@ -673,11 +673,10 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len)
 		WARN_ON_ONCE(xdr->iov);
 		return;
 	}
-	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;
-- 
2.14.5