From patchwork Sun Jul 16 19:49:19 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 13314885 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 C1CAAC001B0 for ; Sun, 16 Jul 2023 20:25:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231971AbjGPUZx (ORCPT ); Sun, 16 Jul 2023 16:25:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231960AbjGPUZx (ORCPT ); Sun, 16 Jul 2023 16:25:53 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E04E126; Sun, 16 Jul 2023 13:25:52 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 6F20060EB8; Sun, 16 Jul 2023 20:25:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7D635C433C7; Sun, 16 Jul 2023 20:25:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689539150; bh=b5jYpXaLjk37pPgAtcwsnC1KhoL/fjS2x3R3vWleLrM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eWmzB9m93EbzH53kVw+FZziS5sXAfWrGt7sWwAiqFw+W99xTZwZMyH5yBF/rmvUVl dkNVX+6J1vgjhJzZgCYK7+tcU9QdkvZA4CTTmN7MC3+dunoQbvuHCdxWWPLipPHBuN 7mZX7GrG+hlAcAxAXdsEIp5EE3Ip09pg90HVi+Lo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Marc Dionne , David Howells , Jeffrey Altman , linux-afs@lists.infradead.org, linux-fsdevel@vger.kernel.org, Linus Torvalds , Sasha Levin Subject: [PATCH 6.4 706/800] afs: Fix accidental truncation when storing data Date: Sun, 16 Jul 2023 21:49:19 +0200 Message-ID: <20230716195005.518850837@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194949.099592437@linuxfoundation.org> References: <20230716194949.099592437@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: David Howells [ Upstream commit 03275585cabd0240944f19f33d7584a1b099a3a8 ] When an AFS FS.StoreData RPC call is made, amongst other things it is given the resultant file size to be. On the server, this is processed by truncating the file to new size and then writing the data. Now, kafs has a lock (vnode->io_lock) that serves to serialise operations against a specific vnode (ie. inode), but the parameters for the op are set before the lock is taken. This allows two writebacks (say sync and kswapd) to race - and if writes are ongoing the writeback for a later write could occur before the writeback for an earlier one if the latter gets interrupted. Note that afs_writepages() cannot take i_mutex and only takes a shared lock on vnode->validate_lock. Also note that the server does the truncation and the write inside a lock, so there's no problem at that end. Fix this by moving the calculation for the proposed new i_size inside the vnode->io_lock. Also reset the iterator (which we might have read from) and update the mtime setting there. Fixes: bd80d8a80e12 ("afs: Use ITER_XARRAY for writing") Reported-by: Marc Dionne Signed-off-by: David Howells Reviewed-by: Jeffrey Altman Reviewed-by: Marc Dionne cc: linux-afs@lists.infradead.org cc: linux-fsdevel@vger.kernel.org Link: https://lore.kernel.org/r/3526895.1687960024@warthog.procyon.org.uk/ Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- fs/afs/write.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fs/afs/write.c b/fs/afs/write.c index 8750b99c3f566..c1f4391ccd7c6 100644 --- a/fs/afs/write.c +++ b/fs/afs/write.c @@ -413,17 +413,19 @@ static int afs_store_data(struct afs_vnode *vnode, struct iov_iter *iter, loff_t afs_op_set_vnode(op, 0, vnode); op->file[0].dv_delta = 1; op->file[0].modification = true; - op->store.write_iter = iter; op->store.pos = pos; op->store.size = size; - op->store.i_size = max(pos + size, vnode->netfs.remote_i_size); op->store.laundering = laundering; - op->mtime = vnode->netfs.inode.i_mtime; op->flags |= AFS_OPERATION_UNINTR; op->ops = &afs_store_data_operation; try_next_key: afs_begin_vnode_operation(op); + + op->store.write_iter = iter; + op->store.i_size = max(pos + size, vnode->netfs.remote_i_size); + op->mtime = vnode->netfs.inode.i_mtime; + afs_wait_for_operation(op); switch (op->error) {