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=-12.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED 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 C0897C43381 for ; Thu, 21 Mar 2019 05:52:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 910F8218AE for ; Thu, 21 Mar 2019 05:52:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553147529; bh=AJEk01NkZ1Wh0Ypf5/XuNm5XIM83dGOE0pPTWTmLEBM=; h=Subject:To:From:Date:List-ID:From; b=XKmb0v0A8FeiUgRCAVjWzvCxfq7MWKvDK5LGii5EAp39ZJ8FSKoql6EugT6x8rk64 NO7OnYGVMbO5P+Saq7r9OlwBIXnpYrmf98n03T7ZG1CnBwz6apskocRmc/3ADTZdjq dpsfLRbhoKCFMnDeFErSxjd2WKWIjewmxpsz1y/U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726025AbfCUFwJ (ORCPT ); Thu, 21 Mar 2019 01:52:09 -0400 Received: from mail.kernel.org ([198.145.29.99]:54298 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725993AbfCUFwI (ORCPT ); Thu, 21 Mar 2019 01:52:08 -0400 Received: from localhost (5356596B.cm-6-7b.dynamic.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 928DD218A2; Thu, 21 Mar 2019 05:52:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553147528; bh=AJEk01NkZ1Wh0Ypf5/XuNm5XIM83dGOE0pPTWTmLEBM=; h=Subject:To:From:Date:From; b=EqKcR9LLrALgNdB1VLaSoBqFNiKhod3EymAzIlKGd45sTiic1rCHnN4y2oGQaZDIp sS/riXyzyK0xIWosVLkK0miTn6WD74cm/2XlNPVumVwrB9cjBkGDrlkr3ureaiJ5+H Khxk0PXk1dC/Z1FYjTIazgk6SvpHz20uAPKcfgsg= Subject: patch "binder: fix race between munmap() and direct reclaim" added to char-misc-linus To: tkjos@android.com, gregkh@linuxfoundation.org, joel@joelfernandes.org, stable@vger.kernel.org, tkjos@google.com From: Date: Thu, 21 Mar 2019 06:51:57 +0100 Message-ID: <1553147517206177@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org This is a note to let you know that I've just added the patch titled binder: fix race between munmap() and direct reclaim to my char-misc git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc.git in the char-misc-linus branch. The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.) The patch will hopefully also be merged in Linus's tree for the next -rc kernel release. If you have any questions about this process, please let me know. >From 5cec2d2e5839f9c0fec319c523a911e0a7fd299f Mon Sep 17 00:00:00 2001 From: Todd Kjos Date: Fri, 1 Mar 2019 15:06:06 -0800 Subject: binder: fix race between munmap() and direct reclaim An munmap() on a binder device causes binder_vma_close() to be called which clears the alloc->vma pointer. If direct reclaim causes binder_alloc_free_page() to be called, there is a race where alloc->vma is read into a local vma pointer and then used later after the mm->mmap_sem is acquired. This can result in calling zap_page_range() with an invalid vma which manifests as a use-after-free in zap_page_range(). The fix is to check alloc->vma after acquiring the mmap_sem (which we were acquiring anyway) and skip zap_page_range() if it has changed to NULL. Signed-off-by: Todd Kjos Reviewed-by: Joel Fernandes (Google) Cc: stable Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 6389467670a0..195f120c4e8c 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -927,14 +927,13 @@ enum lru_status binder_alloc_free_page(struct list_head *item, index = page - alloc->pages; page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE; + + mm = alloc->vma_vm_mm; + if (!mmget_not_zero(mm)) + goto err_mmget; + if (!down_write_trylock(&mm->mmap_sem)) + goto err_down_write_mmap_sem_failed; vma = binder_alloc_get_vma(alloc); - if (vma) { - if (!mmget_not_zero(alloc->vma_vm_mm)) - goto err_mmget; - mm = alloc->vma_vm_mm; - if (!down_read_trylock(&mm->mmap_sem)) - goto err_down_write_mmap_sem_failed; - } list_lru_isolate(lru, item); spin_unlock(lock); @@ -945,10 +944,9 @@ enum lru_status binder_alloc_free_page(struct list_head *item, zap_page_range(vma, page_addr, PAGE_SIZE); trace_binder_unmap_user_end(alloc, index); - - up_read(&mm->mmap_sem); - mmput(mm); } + up_write(&mm->mmap_sem); + mmput(mm); trace_binder_unmap_kernel_start(alloc, index); -- 2.21.0