From patchwork Mon Mar 23 16:07:07 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jeffrey Layton X-Patchwork-Id: 11453389 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 CB4D81668 for ; Mon, 23 Mar 2020 16:07:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F95520637 for ; Mon, 23 Mar 2020 16:07:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584979636; bh=5+j2drKZa+CQfEsajNfhjZNzFm4sp+fulTVSSukQduM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=U2Dr2ZIlxY26CbDgojjQsxCDbxHGfooZXG19q+N5reQzcsPWg0u8nNQz8kxtpQunG uqlLmSLaFwwBJGtdJ0NkormB0xzcCA7/RxFpxTSfawkUnBz/sURqbZvePafwjnvCfa tNm8dGk4O78hhIxNnRieTxHrVXTTTF6lUdH/9r0I= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727609AbgCWQHQ (ORCPT ); Mon, 23 Mar 2020 12:07:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:49506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727594AbgCWQHP (ORCPT ); Mon, 23 Mar 2020 12:07:15 -0400 Received: from tleilax.com (68-20-15-154.lightspeed.rlghnc.sbcglobal.net [68.20.15.154]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E1E4D2072D; Mon, 23 Mar 2020 16:07:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584979635; bh=5+j2drKZa+CQfEsajNfhjZNzFm4sp+fulTVSSukQduM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SlWlE2lrT1YX8heEWyLDXaiyW5YE6mwD09HocuIj1Cz+oLK0mDGcYHc97AwPAJO06 KscuXXsP6jt8SoV+B/BURnH4tw0fxkpriYFg/GRaCKWS5d3mrGVB6LFOVXUCSopHN4 fhtkhhJ1v0p/90I7cgoM/vrVp7tZ49kKieVdF4no= From: Jeff Layton To: ceph-devel@vger.kernel.org Cc: ukernel@gmail.com, idryomov@gmail.com, sage@redhat.com Subject: [PATCH 7/8] ceph: fix potential race in ceph_check_caps Date: Mon, 23 Mar 2020 12:07:07 -0400 Message-Id: <20200323160708.104152-8-jlayton@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200323160708.104152-1-jlayton@kernel.org> References: <20200323160708.104152-1-jlayton@kernel.org> MIME-Version: 1.0 Sender: ceph-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: ceph-devel@vger.kernel.org Nothing ensures that session will still be valid by the time we dereference the pointer. Take and put a reference. Signed-off-by: Jeff Layton --- fs/ceph/caps.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/ceph/caps.c b/fs/ceph/caps.c index 3eab905ba74b..061e52912991 100644 --- a/fs/ceph/caps.c +++ b/fs/ceph/caps.c @@ -2051,12 +2051,14 @@ void ceph_check_caps(struct ceph_inode_info *ci, int flags, if (mutex_trylock(&session->s_mutex) == 0) { dout("inverting session/ino locks on %p\n", session); + session = ceph_get_mds_session(session); spin_unlock(&ci->i_ceph_lock); if (took_snap_rwsem) { up_read(&mdsc->snap_rwsem); took_snap_rwsem = 0; } mutex_lock(&session->s_mutex); + ceph_put_mds_session(session); goto retry; } }