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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0B422C4332F for ; Wed, 9 Nov 2022 14:49:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231673AbiKIOtR (ORCPT ); Wed, 9 Nov 2022 09:49:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231679AbiKIOtF (ORCPT ); Wed, 9 Nov 2022 09:49:05 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CABB1C10B for ; Wed, 9 Nov 2022 06:49:04 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 2BB9F61AA9 for ; Wed, 9 Nov 2022 14:49:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E3B4C433C1; Wed, 9 Nov 2022 14:49:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1668005343; bh=wTUAKlTQa3n4ie4SNGxTrQEkGFFEnmGoUC7BteTRmUw=; h=Subject:To:From:Date:From; b=MNbVHkLOl2dKxDRMcUbl+iG3x2Tcgq8V2MpsWWEfPOaJ9FsHyxN8E1OTaQWV6rvot Q6puQlK+zC4q4Bj5yii7ypmxMz7ecdCacWe8jN2gV+OsaIEEE2n48TXVKDhcMbKndk DDSqKdUA6+nXGmRq3Dt61o5O4J8AwzE9MuWYjFlA= Subject: patch "binder: validate alloc->mm in ->mmap() handler" added to char-misc-linus To: cmllamas@google.com, gregkh@linuxfoundation.org, jannh@google.com, stable@vger.kernel.org, tkjos@google.com From: Date: Wed, 09 Nov 2022 15:49:00 +0100 Message-ID: <166800534023179@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit 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: validate alloc->mm in ->mmap() handler 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 3ce00bb7e91cf57d723905371507af57182c37ef Mon Sep 17 00:00:00 2001 From: Carlos Llamas Date: Fri, 4 Nov 2022 23:12:35 +0000 Subject: binder: validate alloc->mm in ->mmap() handler Since commit 1da52815d5f1 ("binder: fix alloc->vma_vm_mm null-ptr dereference") binder caches a pointer to the current->mm during open(). This fixes a null-ptr dereference reported by syzkaller. Unfortunately, it also opens the door for a process to update its mm after the open(), (e.g. via execve) making the cached alloc->mm pointer invalid. Things get worse when the process continues to mmap() a vma. From this point forward, binder will attempt to find this vma using an obsolete alloc->mm reference. Such as in binder_update_page_range(), where the wrong vma is obtained via vma_lookup(), yet binder proceeds to happily insert new pages into it. To avoid this issue fail the ->mmap() callback if we detect a mismatch between the vma->vm_mm and the original alloc->mm pointer. This prevents alloc->vm_addr from getting set, so that any subsequent vma_lookup() calls fail as expected. Fixes: 1da52815d5f1 ("binder: fix alloc->vma_vm_mm null-ptr dereference") Reported-by: Jann Horn Cc: # 5.15+ Signed-off-by: Carlos Llamas Acked-by: Todd Kjos Link: https://lore.kernel.org/r/20221104231235.348958-1-cmllamas@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/android/binder_alloc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c index 1c39cfce32fa..4ad42b0f75cd 100644 --- a/drivers/android/binder_alloc.c +++ b/drivers/android/binder_alloc.c @@ -739,6 +739,12 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc, const char *failure_string; struct binder_buffer *buffer; + if (unlikely(vma->vm_mm != alloc->mm)) { + ret = -EINVAL; + failure_string = "invalid vma->vm_mm"; + goto err_invalid_mm; + } + mutex_lock(&binder_alloc_mmap_lock); if (alloc->buffer_size) { ret = -EBUSY; @@ -785,6 +791,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc, alloc->buffer_size = 0; err_already_mapped: mutex_unlock(&binder_alloc_mmap_lock); +err_invalid_mm: binder_alloc_debug(BINDER_DEBUG_USER_ERROR, "%s: %d %lx-%lx %s failed %d\n", __func__, alloc->pid, vma->vm_start, vma->vm_end, -- 2.38.1