From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 326F28BE0 for ; Tue, 28 Mar 2023 14:47:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9681C4339E; Tue, 28 Mar 2023 14:47:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680014837; bh=OjCHyWVB1kb32huPEFPJqNwW1O4zE+vHGvq+hU5r4Kg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=opSlqdS2aulIJblp1/75zlkv/4ViIIQKsOGL7R4eXtIMqK5sZ6PCU41ThOor667Oy +AJknv1rPp0S1FFrmPAJD1yjqJih6TFObQyVxC//gECTlqxgmhDs0Us2r8NCBrkE4r IFrVE/OtrdNiWJmZE7x02EUTMlUJNyD3tuCaUGME= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro , Dario Lesca , David Critch , Jeff Layton , Chuck Lever , Sasha Levin Subject: [PATCH 6.2 040/240] nfsd: dont replace page in rq_pages if its a continuation of last page Date: Tue, 28 Mar 2023 16:40:03 +0200 Message-Id: <20230328142621.260573786@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230328142619.643313678@linuxfoundation.org> References: <20230328142619.643313678@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jeff Layton [ Upstream commit 27c934dd8832dd40fd34776f916dc201e18b319b ] 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 Signed-off-by: Sasha Levin --- 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 bb1e85586dfdd..5308070a47f38 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -937,8 +937,15 @@ 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; -- 2.39.2