From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:52954 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2436568AbeHATSi (ORCPT ); Wed, 1 Aug 2018 15:18:38 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Noam Rathaus , Cong Wang , Jason Gunthorpe , Sasha Levin Subject: [PATCH 4.17 050/336] infiniband: fix a possible use-after-free bug Date: Wed, 1 Aug 2018 18:46:25 +0200 Message-Id: <20180801165030.992013153@linuxfoundation.org> In-Reply-To: <20180801165028.930831994@linuxfoundation.org> References: <20180801165028.930831994@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 4.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang [ Upstream commit cb2595c1393b4a5211534e6f0a0fbad369e21ad8 ] ucma_process_join() will free the new allocated "mc" struct, if there is any error after that, especially the copy_to_user(). But in parallel, ucma_leave_multicast() could find this "mc" through idr_find() before ucma_process_join() frees it, since it is already published. So "mc" could be used in ucma_leave_multicast() after it is been allocated and freed in ucma_process_join(), since we don't refcnt it. Fix this by separating "publish" from ID allocation, so that we can get an ID first and publish it later after copy_to_user(). Fixes: c8f6a362bf3e ("RDMA/cma: Add multicast communication support") Reported-by: Noam Rathaus Signed-off-by: Cong Wang Signed-off-by: Jason Gunthorpe Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/ucma.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -235,7 +235,7 @@ static struct ucma_multicast* ucma_alloc return NULL; mutex_lock(&mut); - mc->id = idr_alloc(&multicast_idr, mc, 0, 0, GFP_KERNEL); + mc->id = idr_alloc(&multicast_idr, NULL, 0, 0, GFP_KERNEL); mutex_unlock(&mut); if (mc->id < 0) goto error; @@ -1421,6 +1421,10 @@ static ssize_t ucma_process_join(struct goto err3; } + mutex_lock(&mut); + idr_replace(&multicast_idr, mc, mc->id); + mutex_unlock(&mut); + mutex_unlock(&file->mut); ucma_put_ctx(ctx); return 0;