From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35380 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754518AbeANIKK (ORCPT ); Sun, 14 Jan 2018 03:10:10 -0500 Subject: Patch "staging: android: ashmem: fix a race condition in ASHMEM_SET_SIZE ioctl" has been added to the 4.9-stable tree To: viktors@google.com, gregkh@linuxfoundation.org Cc: , From: Date: Sun, 14 Jan 2018 09:10:00 +0100 Message-ID: <151591740036134@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 List-ID: This is a note to let you know that I've just added the patch titled staging: android: ashmem: fix a race condition in ASHMEM_SET_SIZE ioctl to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: staging-android-ashmem-fix-a-race-condition-in-ashmem_set_size-ioctl.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 443064cb0b1fb4569fe0a71209da7625129fb760 Mon Sep 17 00:00:00 2001 From: Viktor Slavkovic Date: Mon, 8 Jan 2018 10:43:03 -0800 Subject: staging: android: ashmem: fix a race condition in ASHMEM_SET_SIZE ioctl From: Viktor Slavkovic commit 443064cb0b1fb4569fe0a71209da7625129fb760 upstream. A lock-unlock is missing in ASHMEM_SET_SIZE ioctl which can result in a race condition when mmap is called. After the !asma->file check, before setting asma->size, asma->file can be set in mmap. That would result in having different asma->size than the mapped memory size. Combined with ASHMEM_UNPIN ioctl and shrinker invocation, this can result in memory corruption. Signed-off-by: Viktor Slavkovic Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ashmem.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -774,10 +774,12 @@ static long ashmem_ioctl(struct file *fi break; case ASHMEM_SET_SIZE: ret = -EINVAL; + mutex_lock(&ashmem_mutex); if (!asma->file) { ret = 0; asma->size = (size_t)arg; } + mutex_unlock(&ashmem_mutex); break; case ASHMEM_GET_SIZE: ret = asma->size; Patches currently in stable-queue which might be from viktors@google.com are queue-4.9/staging-android-ashmem-fix-a-race-condition-in-ashmem_set_size-ioctl.patch