From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 47ABDC433FF for ; Fri, 2 Aug 2019 09:56:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FFB720578 for ; Fri, 2 Aug 2019 09:56:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739786; bh=TZyC/e3XWGinl9VbLp32LC4zDGiye8OtkVuPC0YrCuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Yqxdj+IR3KAbo2aE5lysPMvJNPpXI7/OUu0nUdzhjiOa53TA5IMMPAzay2hcYTnUK 9XJBMhRHPk212gtz0K0u/hRUgEY0rUQbZ7njXaZLAnKIJfZrBs64O7IOX/3XDXzPPm Z8fXnV46lAk7A/rjEdK+8kzCrcagLMs8WOnhAJwk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2406732AbfHBJ4Y (ORCPT ); Fri, 2 Aug 2019 05:56:24 -0400 Received: from mail.kernel.org ([198.145.29.99]:35116 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2406713AbfHBJ4Q (ORCPT ); Fri, 2 Aug 2019 05:56:16 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 805432064A; Fri, 2 Aug 2019 09:56:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739776; bh=TZyC/e3XWGinl9VbLp32LC4zDGiye8OtkVuPC0YrCuY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I2gQdk93RCDDpAzTQO/DBEAmBgusyW/DXt5snZZymcg2PbHWU9+YnNA3KvHXGJN8b 8VB+uta3i+ZAz7Kq5WP+bXcPzkHU8TTY++tv0gcAlm6+ysCBn8EqXF7gklJ1roFi6x x7GF/yaCXX6rKfGDGvFwcuBb+WGIxcwmZQtpt0cE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Todd Kjos Subject: [PATCH 4.19 09/32] binder: fix possible UAF when freeing buffer Date: Fri, 2 Aug 2019 11:39:43 +0200 Message-Id: <20190802092104.545353007@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092101.913646560@linuxfoundation.org> References: <20190802092101.913646560@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Todd Kjos commit a370003cc301d4361bae20c9ef615f89bf8d1e8a upstream. There is a race between the binder driver cleaning up a completed transaction via binder_free_transaction() and a user calling binder_ioctl(BC_FREE_BUFFER) to release a buffer. It doesn't matter which is first but they need to be protected against running concurrently which can result in a UAF. Signed-off-by: Todd Kjos Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -1960,8 +1960,18 @@ static struct binder_thread *binder_get_ static void binder_free_transaction(struct binder_transaction *t) { - if (t->buffer) - t->buffer->transaction = NULL; + struct binder_proc *target_proc = t->to_proc; + + if (target_proc) { + binder_inner_proc_lock(target_proc); + if (t->buffer) + t->buffer->transaction = NULL; + binder_inner_proc_unlock(target_proc); + } + /* + * If the transaction has no target_proc, then + * t->buffer->transaction has already been cleared. + */ kfree(t); binder_stats_deleted(BINDER_STAT_TRANSACTION); } @@ -3484,10 +3494,12 @@ static int binder_thread_write(struct bi buffer->debug_id, buffer->transaction ? "active" : "finished"); + binder_inner_proc_lock(proc); if (buffer->transaction) { buffer->transaction->buffer = NULL; buffer->transaction = NULL; } + binder_inner_proc_unlock(proc); if (buffer->async_transaction && buffer->target_node) { struct binder_node *buf_node; struct binder_work *w;