From patchwork Wed Dec 4 13:38:06 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: =?utf-8?q?Aur=C3=A9lien_Aptel?= X-Patchwork-Id: 11272969 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 01A99109A for ; Wed, 4 Dec 2019 13:38:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D4D892077B for ; Wed, 4 Dec 2019 13:38:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727703AbfLDNif (ORCPT ); Wed, 4 Dec 2019 08:38:35 -0500 Received: from mx2.suse.de ([195.135.220.15]:39016 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727530AbfLDNif (ORCPT ); Wed, 4 Dec 2019 08:38:35 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id B1675B38D; Wed, 4 Dec 2019 13:38:33 +0000 (UTC) From: Aurelien Aptel To: linux-cifs@vger.kernel.org Cc: smfrench@gmail.com, Aurelien Aptel Subject: [PATCH] cifs: fix possible uninitialized access and race on iface_list Date: Wed, 4 Dec 2019 14:38:06 +0100 Message-Id: <20191204133806.27431-1-aaptel@suse.com> X-Mailer: git-send-email 2.16.4 Sender: linux-cifs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-cifs@vger.kernel.org iface[0] was accessed regardless of the count value and without locking. * check count before accessing any ifaces * make copy of iface list (it's a simple POD array) and use it without locking. Signed-off-by: Aurelien Aptel --- fs/cifs/sess.c | 30 +++++++++++++++++++++++++++--- 1 file changed, 27 insertions(+), 3 deletions(-) diff --git a/fs/cifs/sess.c b/fs/cifs/sess.c index fb3bdc44775c..6a58f8a477a2 100644 --- a/fs/cifs/sess.c +++ b/fs/cifs/sess.c @@ -77,6 +77,8 @@ int cifs_try_adding_channels(struct cifs_ses *ses) int i = 0; int rc = 0; int tries = 0; + struct cifs_server_iface *ifaces = NULL; + size_t iface_count; if (left <= 0) { cifs_dbg(FYI, @@ -90,6 +92,27 @@ int cifs_try_adding_channels(struct cifs_ses *ses) return 0; } + /* + * Make a copy of the iface list at the time and use that + * instead so as to not hold the iface spinlock for opening + * channels + */ + spin_lock(&ses->iface_lock); + iface_count = ses->iface_count; + if (iface_count <= 0) { + spin_unlock(&ses->iface_lock); + cifs_dbg(FYI, "no iface list available to open channels\n"); + return 0; + } + ifaces = kmemdup(ses->iface_list, iface_count*sizeof(*ifaces), + GFP_ATOMIC); + if (!ifaces) { + spin_unlock(&ses->iface_lock); + kfree(ifaces); + return 0; + } + spin_unlock(&ses->iface_lock); + /* * Keep connecting to same, fastest, iface for all channels as * long as its RSS. Try next fastest one if not RSS or channel @@ -105,9 +128,9 @@ int cifs_try_adding_channels(struct cifs_ses *ses) break; } - iface = &ses->iface_list[i]; + iface = &ifaces[i]; if (is_ses_using_iface(ses, iface) && !iface->rss_capable) { - i = (i+1) % ses->iface_count; + i = (i+1) % iface_count; continue; } @@ -115,7 +138,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses) if (rc) { cifs_dbg(FYI, "failed to open extra channel on iface#%d rc=%d\n", i, rc); - i = (i+1) % ses->iface_count; + i = (i+1) % iface_count; continue; } @@ -124,6 +147,7 @@ int cifs_try_adding_channels(struct cifs_ses *ses) left--; } + kfree(ifaces); return ses->chan_count - old_chan_count; }