From 7b86a9a6c9fe6ae8c810121a2396dc3a652c8b67 Mon Sep 17 00:00:00 2001 From: Frank Sorenson Date: Tue, 30 Oct 2018 15:10:40 -0500 Subject: [PATCH] sunrpc: correct the computation for page_ptr when truncating 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 Cc: stable@vger.kernel.org Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- 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 2a81e77..6de975a 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -638,11 +638,10 @@ void xdr_truncate_encode(struct xdr_stream *xdr, size_t len) /* xdr->iov should already be NULL */ 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; -- 2.7.4