sunrpc: correct the computation for page_ptr when truncating
authorFrank Sorenson <sorenson@redhat.com>
Tue, 30 Oct 2018 20:10:40 +0000 (15:10 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 21 Nov 2018 08:24:14 +0000 (09:24 +0100)
commita56609f725c3cfff71e0878036263477d59755a4
tree6685d0fd55b9fec13544be3ff40338eba43b6980
parentdedde93bd683730e78da54db42e52cb87cdb8a0c
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 <sorenson@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
net/sunrpc/xdr.c