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- From 782a4580a5e347793443aa8e9152db1bf4a0fff8 Mon Sep 17 00:00:00 2001
- From: Peter Jones <pjones@redhat.com>
- Date: Mon, 15 Jun 2020 10:58:42 -0400
- Subject: [PATCH] safemath: Add some arithmetic primitives that check for
- overflow
- MIME-Version: 1.0
- Content-Type: text/plain; charset=UTF-8
- Content-Transfer-Encoding: 8bit
- This adds a new header, include/grub/safemath.h, that includes easy to
- use wrappers for __builtin_{add,sub,mul}_overflow() declared like:
- bool OP(a, b, res)
- where OP is grub_add, grub_sub or grub_mul. OP() returns true in the
- case where the operation would overflow and res is not modified.
- Otherwise, false is returned and the operation is executed.
- These arithmetic primitives require newer compiler versions. So, bump
- these requirements in the INSTALL file too.
- Signed-off-by: Peter Jones <pjones@redhat.com>
- Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
- Signed-off-by: Stefan Sørensen <stefan.sorensen@spectralink.com>
- ---
- INSTALL | 22 ++--------------------
- include/grub/compiler.h | 8 ++++++++
- include/grub/safemath.h | 37 +++++++++++++++++++++++++++++++++++++
- 3 files changed, 47 insertions(+), 20 deletions(-)
- create mode 100644 include/grub/safemath.h
- diff --git a/INSTALL b/INSTALL
- index 8acb40902..dcb9b7d7b 100644
- --- a/INSTALL
- +++ b/INSTALL
- @@ -11,27 +11,9 @@ GRUB depends on some software packages installed into your system. If
- you don't have any of them, please obtain and install them before
- configuring the GRUB.
-
- -* GCC 4.1.3 or later
- - Note: older versions may work but support is limited
- -
- - Experimental support for clang 3.3 or later (results in much bigger binaries)
- +* GCC 5.1.0 or later
- + Experimental support for clang 3.8.0 or later (results in much bigger binaries)
- for i386, x86_64, arm (including thumb), arm64, mips(el), powerpc, sparc64
- - Note: clang 3.2 or later works for i386 and x86_64 targets but results in
- - much bigger binaries.
- - earlier versions not tested
- - Note: clang 3.2 or later works for arm
- - earlier versions not tested
- - Note: clang on arm64 is not supported due to
- - https://llvm.org/bugs/show_bug.cgi?id=26030
- - Note: clang 3.3 or later works for mips(el)
- - earlier versions fail to generate .reginfo and hence gprel relocations
- - fail.
- - Note: clang 3.2 or later works for powerpc
- - earlier versions not tested
- - Note: clang 3.5 or later works for sparc64
- - earlier versions return "error: unable to interface with target machine"
- - Note: clang has no support for ia64 and hence you can't compile GRUB
- - for ia64 with clang
- * GNU Make
- * GNU Bison 2.3 or later
- * GNU gettext 0.17 or later
- diff --git a/include/grub/compiler.h b/include/grub/compiler.h
- index c9e1d7a73..8f3be3ae7 100644
- --- a/include/grub/compiler.h
- +++ b/include/grub/compiler.h
- @@ -48,4 +48,12 @@
- # define WARN_UNUSED_RESULT
- #endif
-
- +#if defined(__clang__) && defined(__clang_major__) && defined(__clang_minor__)
- +# define CLANG_PREREQ(maj,min) \
- + ((__clang_major__ > (maj)) || \
- + (__clang_major__ == (maj) && __clang_minor__ >= (min)))
- +#else
- +# define CLANG_PREREQ(maj,min) 0
- +#endif
- +
- #endif /* ! GRUB_COMPILER_HEADER */
- diff --git a/include/grub/safemath.h b/include/grub/safemath.h
- new file mode 100644
- index 000000000..c17b89bba
- --- /dev/null
- +++ b/include/grub/safemath.h
- @@ -0,0 +1,37 @@
- +/*
- + * GRUB -- GRand Unified Bootloader
- + * Copyright (C) 2020 Free Software Foundation, Inc.
- + *
- + * GRUB is free software: you can redistribute it and/or modify
- + * it under the terms of the GNU General Public License as published by
- + * the Free Software Foundation, either version 3 of the License, or
- + * (at your option) any later version.
- + *
- + * GRUB is distributed in the hope that it will be useful,
- + * but WITHOUT ANY WARRANTY; without even the implied warranty of
- + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
- + * GNU General Public License for more details.
- + *
- + * You should have received a copy of the GNU General Public License
- + * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
- + *
- + * Arithmetic operations that protect against overflow.
- + */
- +
- +#ifndef GRUB_SAFEMATH_H
- +#define GRUB_SAFEMATH_H 1
- +
- +#include <grub/compiler.h>
- +
- +/* These appear in gcc 5.1 and clang 3.8. */
- +#if GNUC_PREREQ(5, 1) || CLANG_PREREQ(3, 8)
- +
- +#define grub_add(a, b, res) __builtin_add_overflow(a, b, res)
- +#define grub_sub(a, b, res) __builtin_sub_overflow(a, b, res)
- +#define grub_mul(a, b, res) __builtin_mul_overflow(a, b, res)
- +
- +#else
- +#error gcc 5.1 or newer or clang 3.8 or newer is required
- +#endif
- +
- +#endif /* GRUB_SAFEMATH_H */
- --
- 2.26.2
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