From: Frank Sorenson Date: Tue, 30 Oct 2018 20:10:40 +0000 (-0500) Subject: sunrpc: correct the computation for page_ptr when truncating X-Git-Tag: rel_imx_4.19.35_1.1.0~8556 X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=03c91663c0935fd1c7df5539ff6df65db8f57278;p=linux.git 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 --- diff --git a/net/sunrpc/xdr.c b/net/sunrpc/xdr.c index 30afbd236656..b53cc0960b5d 100644 --- a/net/sunrpc/xdr.c +++ b/net/sunrpc/xdr.c @@ -639,11 +639,10 @@ 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;