From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:43278 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731020AbeJKXLX (ORCPT ); Thu, 11 Oct 2018 19:11:23 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+cfe3c1e8ef634ba8964b@syzkaller.appspotmail.com, Jason Gunthorpe , Doug Ledford , Leon Romanovsky , Cong Wang , Leon Romanovsky Subject: [PATCH 4.9 25/35] ucma: fix a use-after-free in ucma_resolve_ip() Date: Thu, 11 Oct 2018 17:35:27 +0200 Message-Id: <20181011152521.180580326@linuxfoundation.org> In-Reply-To: <20181011152520.174949126@linuxfoundation.org> References: <20181011152520.174949126@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Cong Wang commit 5fe23f262e0548ca7f19fb79f89059a60d087d22 upstream. There is a race condition between ucma_close() and ucma_resolve_ip(): CPU0 CPU1 ucma_resolve_ip(): ucma_close(): ctx = ucma_get_ctx(file, cmd.id); list_for_each_entry_safe(ctx, tmp, &file->ctx_list, list) { mutex_lock(&mut); idr_remove(&ctx_idr, ctx->id); mutex_unlock(&mut); ... mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); rdma_destroy_id(ctx->cm_id); ... ucma_free_ctx(ctx); ret = rdma_resolve_addr(); ucma_put_ctx(ctx); Before idr_remove(), ucma_get_ctx() could still find the ctx and after rdma_destroy_id(), rdma_resolve_addr() may still access id_priv pointer. Also, ucma_put_ctx() may use ctx after ucma_free_ctx() too. ucma_close() should call ucma_put_ctx() too which tests the refcnt and waits for the last one releasing it. The similar pattern is already used by ucma_destroy_id(). Reported-and-tested-by: syzbot+da2591e115d57a9cbb8b@syzkaller.appspotmail.com Reported-by: syzbot+cfe3c1e8ef634ba8964b@syzkaller.appspotmail.com Cc: Jason Gunthorpe Cc: Doug Ledford Cc: Leon Romanovsky Signed-off-by: Cong Wang Reviewed-by: Leon Romanovsky Signed-off-by: Doug Ledford Signed-off-by: Greg Kroah-Hartman --- drivers/infiniband/core/ucma.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/infiniband/core/ucma.c +++ b/drivers/infiniband/core/ucma.c @@ -1720,6 +1720,8 @@ static int ucma_close(struct inode *inod mutex_lock(&mut); if (!ctx->closing) { mutex_unlock(&mut); + ucma_put_ctx(ctx); + wait_for_completion(&ctx->comp); /* rdma_destroy_id ensures that no event handlers are * inflight for that id before releasing it. */