platform_bionic/libc/private/bionic_constants.h
Peter Collingbourne f1ed31ffe1 Increase the size of the shadow call stack guard region to 16MB.
Increasing the size of the guard region helps with the security of SCS,
but it's blocked on landing [1], which in turn is blocked on landing
[2]. Once those two CLs land we will be able to land this one.

[1] https://android-review.googlesource.com/c/platform/frameworks/av/+/837745
[2] https://android-review.googlesource.com/c/platform/bionic/+/818973

Bug: 118642754
Change-Id: I35409cbb6bfcd77e632567dd755376e345cfe67b
2019-01-31 14:37:34 -08:00

31 lines
1.2 KiB
C

/*
* Copyright (C) 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef _BIONIC_CONSTANTS_H_
#define _BIONIC_CONSTANTS_H_
#define NS_PER_S 1000000000
// Size of the shadow call stack. This must be a power of 2.
#define SCS_SIZE (8 * 1024)
// The shadow call stack is allocated at an aligned address within a guard region of this size. The
// guard region must be large enough that we can allocate an SCS_SIZE-aligned SCS while ensuring
// that there is at least one guard page after the SCS so that a stack overflow results in a SIGSEGV
// instead of corrupting the allocation that comes after it.
#define SCS_GUARD_REGION_SIZE (16 * 1024 * 1024)
#endif // _BIONIC_CONSTANTS_H_