From patchwork Fri Mar 17 23:01:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chuck Lever X-Patchwork-Id: 13179564 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2BE8CC7618E for ; Fri, 17 Mar 2023 23:02:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229934AbjCQXCW (ORCPT ); Fri, 17 Mar 2023 19:02:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34894 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229516AbjCQXCV (ORCPT ); Fri, 17 Mar 2023 19:02:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1D3BB4FF13 for ; Fri, 17 Mar 2023 16:01:59 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2A33A60BC5 for ; Fri, 17 Mar 2023 23:01:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34A28C433EF; Fri, 17 Mar 2023 23:01:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679094086; bh=1hDX9JSkvaA2c2aqNndSO+fLzP94W74efh2KnHoeg9w=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=Qtbx+f6+q/Yu4YpUjnU6Dr9dM4F86BtfJpFDciFsIR6baqv+oSFdYfdDEwbpVBarz FAlNL9XCmivlYWgWeEgbpVbQkxRKokJ2QQqOhCoAMa3gJgFJa16xiin9FvDKdXWrvY fxKlTc3G3xRINDJnZ34Hal78YcYFOFCQRKWXq+2knKPQ1Q5u7EZ4uftFoqD+lUPnCf JP6p04mFd/dF/BghcTp4tbGctWKpv6YvGyvP3ga7dheSXNYoUNrQRH6t7OevmxYaa0 Pgs4UF416G9CXZHpk3uQ4YYHrimtB6ToS4fF0FhkbHTEmUxNHlUy9/FBw0559vvtyX iWdH1r7V20qdw== Subject: [PATCH v1 1/3] nfsd: don't replace page in rq_pages if it's a continuation of last page From: Chuck Lever To: linux-nfs@vger.kernel.org Cc: viro@zeniv.linux.org.uk, dcritch@redhat.com, d.lesca@solinos.it Date: Fri, 17 Mar 2023 19:01:25 -0400 Message-ID: <167909408510.1672.11351348839166110078.stgit@klimt.1015granger.net> In-Reply-To: <167909365790.1672.13118429954916842449.stgit@klimt.1015granger.net> References: <167909365790.1672.13118429954916842449.stgit@klimt.1015granger.net> User-Agent: StGit/1.5 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Jeff Layton The splice read calls nfsd_splice_actor to put the pages containing file data into the svc_rqst->rq_pages array. It's possible however to get a splice result that only has a partial page at the end, if (e.g.) the filesystem hands back a short read that doesn't cover the whole page. nfsd_splice_actor will plop the partial page into its rq_pages array and return. Then later, when nfsd_splice_actor is called again, the remainder of the page may end up being filled out. At this point, nfsd_splice_actor will put the page into the array _again_ corrupting the reply. If this is done enough times, rq_next_page will overrun the array and corrupt the trailing fields -- the rq_respages and rq_next_page pointers themselves. If we've already added the page to the array in the last pass, don't add it to the array a second time when dealing with a splice continuation. This was originally handled properly in nfsd_splice_actor, but commit 91e23b1c3982 ("NFSD: Clean up nfsd_splice_actor()") removed the check for it. Fixes: 91e23b1c3982 ("NFSD: Clean up nfsd_splice_actor()") Cc: Al Viro Reported-by: Dario Lesca Tested-by: David Critch Link: https://bugzilla.redhat.com/show_bug.cgi?id=2150630 Signed-off-by: Jeff Layton Signed-off-by: Chuck Lever --- fs/nfsd/vfs.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 502e1b7742db..5783209f17fc 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -941,8 +941,15 @@ nfsd_splice_actor(struct pipe_inode_info *pipe, struct pipe_buffer *buf, struct page *last_page; last_page = page + (offset + sd->len - 1) / PAGE_SIZE; - for (page += offset / PAGE_SIZE; page <= last_page; page++) + for (page += offset / PAGE_SIZE; page <= last_page; page++) { + /* + * Skip page replacement when extending the contents + * of the current page. + */ + if (page == *(rqstp->rq_next_page - 1)) + continue; svc_rqst_replace_page(rqstp, page); + } if (rqstp->rq_res.page_len == 0) // first call rqstp->rq_res.page_base = offset % PAGE_SIZE; rqstp->rq_res.page_len += sd->len;