From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:35224 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731269AbeJBURh (ORCPT ); Tue, 2 Oct 2018 16:17:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Todd Kjos , devel@driverdev.osuosl.org, kernel-team@android.com, Joel Fernandes , Alistair Strachan , Martijn Coenen , Sasha Levin Subject: [PATCH 4.14 053/137] staging: android: ashmem: Fix mmap size validation Date: Tue, 2 Oct 2018 06:24:14 -0700 Message-Id: <20181002132502.207098989@linuxfoundation.org> In-Reply-To: <20181002132458.446916963@linuxfoundation.org> References: <20181002132458.446916963@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alistair Strachan [ Upstream commit 8632c614565d0c5fdde527889601c018e97b6384 ] The ashmem driver did not check that the size/offset of the vma passed to its .mmap() function was not larger than the ashmem object being mapped. This could cause mmap() to succeed, even though accessing parts of the mapping would later fail with a segmentation fault. Ensure an error is returned by the ashmem_mmap() function if the vma size is larger than the ashmem object size. This enables safer handling of the problem in userspace. Cc: Todd Kjos Cc: devel@driverdev.osuosl.org Cc: linux-kernel@vger.kernel.org Cc: kernel-team@android.com Cc: Joel Fernandes Signed-off-by: Alistair Strachan Acked-by: Joel Fernandes (Google) Reviewed-by: Martijn Coenen Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ashmem.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/drivers/staging/android/ashmem.c +++ b/drivers/staging/android/ashmem.c @@ -374,6 +374,12 @@ static int ashmem_mmap(struct file *file goto out; } + /* requested mapping size larger than object size */ + if (vma->vm_end - vma->vm_start > PAGE_ALIGN(asma->size)) { + ret = -EINVAL; + goto out; + } + /* requested protection bits must match our allowed protection mask */ if (unlikely((vma->vm_flags & ~calc_vm_prot_bits(asma->prot_mask, 0)) & calc_vm_prot_bits(PROT_MASK, 0))) {