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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 6BB8DC433DF for ; Mon, 29 Jun 2020 18:35:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5050521D81 for ; Mon, 29 Jun 2020 18:35:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593455759; bh=PRg3gNddfPH321cMWS/GHKOJAHMlEJ564PRUx9ZgBvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=zkGxkl9whmcs7qNUL59cVbI8TGmPZbckMyzVzSajBmW9qUGZC1aP9SOka8oQA1sf+ URtmcOmvYK+inifGYtMPsPhxRXBQXMXUzo8JxASAdFaZrgHBlw+Tr6Ctn3zpT/XXFS H9OyVHkH7Ux4VAfbDwkPqgikqpYXD9iARAiLElTI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726875AbgF2Sf6 (ORCPT ); Mon, 29 Jun 2020 14:35:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:56784 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726459AbgF2Sf2 (ORCPT ); Mon, 29 Jun 2020 14:35:28 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7CBCA241A4; Mon, 29 Jun 2020 15:19:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1593443957; bh=PRg3gNddfPH321cMWS/GHKOJAHMlEJ564PRUx9ZgBvc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TqYS5MwwTVnA0fu3hOQ366bTClZ9w+34e0YHy0gUcC6GFZsRBdyNp450Lv+FR5b0G wG+rwneJonRZSSqkgg1tlriGDB63a5IhfjPs07tkjsR9TYTJXncO02BBv9lzEOa8Qm uKOlitPmcj47dgCQVD+LycLWIxTCHjVWROybLmXI= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Todd Kjos , Christian Brauner , Greg Kroah-Hartman Subject: [PATCH 5.7 059/265] binder: fix null deref of proc->context Date: Mon, 29 Jun 2020 11:14:52 -0400 Message-Id: <20200629151818.2493727-60-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200629151818.2493727-1-sashal@kernel.org> References: <20200629151818.2493727-1-sashal@kernel.org> MIME-Version: 1.0 X-KernelTest-Patch: http://kernel.org/pub/linux/kernel/v5.x/stable-review/patch-5.7.7-rc1.gz X-KernelTest-Tree: git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable-rc.git X-KernelTest-Branch: linux-5.7.y X-KernelTest-Patches: git://git.kernel.org/pub/scm/linux/kernel/git/stable/stable-queue.git X-KernelTest-Version: 5.7.7-rc1 X-KernelTest-Deadline: 2020-07-01T15:14+00:00 X-stable: review X-Patchwork-Hint: Ignore 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 d35d3660e065b69fdb8bf512f3d899f350afce52 upstream. The binder driver makes the assumption proc->context pointer is invariant after initialization (as documented in the kerneldoc header for struct proc). However, in commit f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") proc->context is set to NULL during binder_deferred_release(). Another proc was in the middle of setting up a transaction to the dying process and crashed on a NULL pointer deref on "context" which is a local set to &proc->context: new_ref->data.desc = (node == context->binder_context_mgr_node) ? 0 : 1; Here's the stack: [ 5237.855435] Call trace: [ 5237.855441] binder_get_ref_for_node_olocked+0x100/0x2ec [ 5237.855446] binder_inc_ref_for_node+0x140/0x280 [ 5237.855451] binder_translate_binder+0x1d0/0x388 [ 5237.855456] binder_transaction+0x2228/0x3730 [ 5237.855461] binder_thread_write+0x640/0x25bc [ 5237.855466] binder_ioctl_write_read+0xb0/0x464 [ 5237.855471] binder_ioctl+0x30c/0x96c [ 5237.855477] do_vfs_ioctl+0x3e0/0x700 [ 5237.855482] __arm64_sys_ioctl+0x78/0xa4 [ 5237.855488] el0_svc_common+0xb4/0x194 [ 5237.855493] el0_svc_handler+0x74/0x98 [ 5237.855497] el0_svc+0x8/0xc The fix is to move the kfree of the binder_device to binder_free_proc() so the binder_device is freed when we know there are no references remaining on the binder_proc. Fixes: f0fe2c0f050d ("binder: prevent UAF for binderfs devices II") Acked-by: Christian Brauner Signed-off-by: Todd Kjos Cc: stable Link: https://lore.kernel.org/r/20200622200715.114382-1-tkjos@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/drivers/android/binder.c b/drivers/android/binder.c index e47c8a4c83db5..f50c5f182bb52 100644 --- a/drivers/android/binder.c +++ b/drivers/android/binder.c @@ -4686,8 +4686,15 @@ static struct binder_thread *binder_get_thread(struct binder_proc *proc) static void binder_free_proc(struct binder_proc *proc) { + struct binder_device *device; + BUG_ON(!list_empty(&proc->todo)); BUG_ON(!list_empty(&proc->delivered_death)); + device = container_of(proc->context, struct binder_device, context); + if (refcount_dec_and_test(&device->ref)) { + kfree(proc->context->name); + kfree(device); + } binder_alloc_deferred_release(&proc->alloc); put_task_struct(proc->tsk); binder_stats_deleted(BINDER_STAT_PROC); @@ -5406,7 +5413,6 @@ static int binder_node_release(struct binder_node *node, int refs) static void binder_deferred_release(struct binder_proc *proc) { struct binder_context *context = proc->context; - struct binder_device *device; struct rb_node *n; int threads, nodes, incoming_refs, outgoing_refs, active_transactions; @@ -5423,12 +5429,6 @@ static void binder_deferred_release(struct binder_proc *proc) context->binder_context_mgr_node = NULL; } mutex_unlock(&context->context_mgr_node_lock); - device = container_of(proc->context, struct binder_device, context); - if (refcount_dec_and_test(&device->ref)) { - kfree(context->name); - kfree(device); - } - proc->context = NULL; binder_inner_proc_lock(proc); /* * Make sure proc stays alive after we -- 2.25.1