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=unavailable 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 F0A31C00454 for ; Wed, 11 Dec 2019 15:26:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C7B6A208C3 for ; Wed, 11 Dec 2019 15:26:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576077980; bh=yKYyV8WCc8qaM7E40q6OGjSrK/U8pEFIfTyF9vhkoGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=EA4VC91BR1UOc4O+prNqlQk92gzsBQLr31ngeQ54tGFOT9hY+kn/4oQSln3O1Lycq UUdHm4fFoc7PcJu6YjK15wIKloFJorbJfuqsr7pWvkQaNPHR3+TwTh4eLvdfoeWX0z YlLVpUrPwjfFJ7P7QmT0Eo2yijEYWEHWUAfafM1E= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733102AbfLKP0T (ORCPT ); Wed, 11 Dec 2019 10:26:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:59422 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732801AbfLKP0R (ORCPT ); Wed, 11 Dec 2019 10:26:17 -0500 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 E595122527; Wed, 11 Dec 2019 15:26:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576077976; bh=yKYyV8WCc8qaM7E40q6OGjSrK/U8pEFIfTyF9vhkoGY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pq+m8OxVp9cmy0WGvCmLoP/oOTJpL9J9icDjaTiHJLEeTJpPetIGSJIbWBSBfN1Uu Wrek7ZjmTy+TOMqQnapHASv7NSU6/81uQLwpiY+ZSLn+KNgy2cKCgq2GCIHICPADOM y0E3HYtFVPVLuVr9hNVVtx/ZSDhSK+28WSI5X4KE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jann Horn , Christian Brauner Subject: [PATCH 4.19 243/243] binder: Handle start==NULL in binder_update_page_range() Date: Wed, 11 Dec 2019 16:06:45 +0100 Message-Id: <20191211150355.743952632@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20191211150339.185439726@linuxfoundation.org> References: <20191211150339.185439726@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: Jann Horn commit 2a9edd056ed4fbf9d2e797c3fc06335af35bccc4 upstream. The old loop wouldn't stop when reaching `start` if `start==NULL`, instead continuing backwards to index -1 and crashing. Luckily you need to be highly privileged to map things at NULL, so it's not a big problem. Fix it by adjusting the loop so that the loop variable is always in bounds. This patch is deliberately minimal to simplify backporting, but IMO this function could use a refactor. The jump labels in the second loop body are horrible (the error gotos should be jumping to free_range instead), and both loops would look nicer if they just iterated upwards through indices. And the up_read()+mmput() shouldn't be duplicated like that. Cc: stable@vger.kernel.org Fixes: 457b9a6f09f0 ("Staging: android: add binder driver") Signed-off-by: Jann Horn Acked-by: Christian Brauner Link: https://lore.kernel.org/r/20191018205631.248274-3-jannh@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -295,8 +295,7 @@ static int binder_update_page_range(stru return 0; free_range: - for (page_addr = end - PAGE_SIZE; page_addr >= start; - page_addr -= PAGE_SIZE) { + for (page_addr = end - PAGE_SIZE; 1; page_addr -= PAGE_SIZE) { bool ret; size_t index; @@ -309,6 +308,8 @@ free_range: WARN_ON(!ret); trace_binder_free_lru_end(alloc, index); + if (page_addr == start) + break; continue; err_vm_insert_page_failed: @@ -318,7 +319,8 @@ err_map_kernel_failed: page->page_ptr = NULL; err_alloc_page_failed: err_page_ptr_cleared: - ; + if (page_addr == start) + break; } err_no_vma: if (mm) {