UBSAN: run-time undefined behavior sanity checker

UBSAN uses compile-time instrumentation to catch undefined behavior
(UB).  Compiler inserts code that perform certain kinds of checks before
operations that could cause UB.  If check fails (i.e.  UB detected)
__ubsan_handle_* function called to print error message.

So the most of the work is done by compiler.  This patch just implements
ubsan handlers printing errors.

GCC has this capability since 4.9.x [1] (see -fsanitize=undefined
option and its suboptions).
However GCC 5.x has more checkers implemented [2].
Article [3] has a bit more details about UBSAN in the GCC.

[1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html
[2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
[3] - http://developerblog.redhat.com/2014/10/16/gcc-undefined-behavior-sanitizer-ubsan/

Issues which UBSAN has found thus far are:

Found bugs:

 * out-of-bounds access - 97840cb67f ("netfilter: nfnetlink: fix
   insufficient validation in nfnetlink_bind")

undefined shifts:

 * d48458d4a7 ("jbd2: use a better hash function for the revoke
   table")

 * 10632008b9 ("clockevents: Prevent shift out of bounds")

 * 'x << -1' shift in ext4 -
   http://lkml.kernel.org/r/<5444EF21.8020501@samsung.com>

 * undefined rol32(0) -
   http://lkml.kernel.org/r/<1449198241-20654-1-git-send-email-sasha.levin@oracle.com>

 * undefined dirty_ratelimit calculation -
   http://lkml.kernel.org/r/<566594E2.3050306@odin.com>

 * undefined roundown_pow_of_two(0) -
   http://lkml.kernel.org/r/<1449156616-11474-1-git-send-email-sasha.levin@oracle.com>

 * [WONTFIX] undefined shift in __bpf_prog_run -
   http://lkml.kernel.org/r/<CACT4Y+ZxoR3UjLgcNdUm4fECLMx2VdtfrENMtRRCdgHB2n0bJA@mail.gmail.com>

   WONTFIX here because it should be fixed in bpf program, not in kernel.

signed overflows:

 * 32a8df4e0b ("sched: Fix odd values in effective_load()
   calculations")

 * mul overflow in ntp -
   http://lkml.kernel.org/r/<1449175608-1146-1-git-send-email-sasha.levin@oracle.com>

 * incorrect conversion into rtc_time in rtc_time64_to_tm() -
   http://lkml.kernel.org/r/<1449187944-11730-1-git-send-email-sasha.levin@oracle.com>

 * unvalidated timespec in io_getevents() -
   http://lkml.kernel.org/r/<CACT4Y+bBxVYLQ6LtOKrKtnLthqLHcw-BMp3aqP3mjdAvr9FULQ@mail.gmail.com>

 * [NOTABUG] signed overflow in ktime_add_safe() -
   http://lkml.kernel.org/r/<CACT4Y+aJ4muRnWxsUe1CMnA6P8nooO33kwG-c8YZg=0Xc8rJqw@mail.gmail.com>

[akpm@linux-foundation.org: fix unused local warning]
[akpm@linux-foundation.org: fix __int128 build woes]
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Marek <mmarek@suse.cz>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Yury Gribov <y.gribov@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Andrey Ryabinin 2016-01-20 15:00:55 -08:00 committed by Linus Torvalds
parent 68920c9732
commit c6d308534a
17 changed files with 693 additions and 1 deletions

84
Documentation/ubsan.txt Normal file
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@ -0,0 +1,84 @@
Undefined Behavior Sanitizer - UBSAN
Overview
--------
UBSAN is a runtime undefined behaviour checker.
UBSAN uses compile-time instrumentation to catch undefined behavior (UB).
Compiler inserts code that perform certain kinds of checks before operations
that may cause UB. If check fails (i.e. UB detected) __ubsan_handle_*
function called to print error message.
GCC has that feature since 4.9.x [1] (see -fsanitize=undefined option and
its suboptions). GCC 5.x has more checkers implemented [2].
Report example
---------------
================================================================================
UBSAN: Undefined behaviour in ../include/linux/bitops.h:110:33
shift exponent 32 is to large for 32-bit type 'unsigned int'
CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.0-rc1+ #26
0000000000000000 ffffffff82403cc8 ffffffff815e6cd6 0000000000000001
ffffffff82403cf8 ffffffff82403ce0 ffffffff8163a5ed 0000000000000020
ffffffff82403d78 ffffffff8163ac2b ffffffff815f0001 0000000000000002
Call Trace:
[<ffffffff815e6cd6>] dump_stack+0x45/0x5f
[<ffffffff8163a5ed>] ubsan_epilogue+0xd/0x40
[<ffffffff8163ac2b>] __ubsan_handle_shift_out_of_bounds+0xeb/0x130
[<ffffffff815f0001>] ? radix_tree_gang_lookup_slot+0x51/0x150
[<ffffffff8173c586>] _mix_pool_bytes+0x1e6/0x480
[<ffffffff83105653>] ? dmi_walk_early+0x48/0x5c
[<ffffffff8173c881>] add_device_randomness+0x61/0x130
[<ffffffff83105b35>] ? dmi_save_one_device+0xaa/0xaa
[<ffffffff83105653>] dmi_walk_early+0x48/0x5c
[<ffffffff831066ae>] dmi_scan_machine+0x278/0x4b4
[<ffffffff8111d58a>] ? vprintk_default+0x1a/0x20
[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
[<ffffffff830b2240>] setup_arch+0x405/0xc2c
[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
[<ffffffff830ae053>] start_kernel+0x83/0x49a
[<ffffffff830ad120>] ? early_idt_handler_array+0x120/0x120
[<ffffffff830ad386>] x86_64_start_reservations+0x2a/0x2c
[<ffffffff830ad4f3>] x86_64_start_kernel+0x16b/0x17a
================================================================================
Usage
-----
To enable UBSAN configure kernel with:
CONFIG_UBSAN=y
and to check the entire kernel:
CONFIG_UBSAN_SANITIZE_ALL=y
To enable instrumentation for specific files or directories, add a line
similar to the following to the respective kernel Makefile:
For a single file (e.g. main.o):
UBSAN_SANITIZE_main.o := y
For all files in one directory:
UBSAN_SANITIZE := y
To exclude files from being instrumented even if
CONFIG_UBSAN_SANITIZE_ALL=y, use:
UBSAN_SANITIZE_main.o := n
and:
UBSAN_SANITIZE := n
Detection of unaligned accesses controlled through the separate option -
CONFIG_UBSAN_ALIGNMENT. It's off by default on architectures that support
unaligned accesses (CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y). One could
still enable it in config, just note that it will produce a lot of UBSAN
reports.
References
----------
[1] - https://gcc.gnu.org/onlinedocs/gcc-4.9.0/gcc/Debugging-Options.html
[2] - https://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html

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@ -411,7 +411,7 @@ export MAKE AWK GENKSYMS INSTALLKERNEL PERL PYTHON UTS_MACHINE
export HOSTCXX HOSTCXXFLAGS LDFLAGS_MODULE CHECK CHECKFLAGS
export KBUILD_CPPFLAGS NOSTDINC_FLAGS LINUXINCLUDE OBJCOPYFLAGS LDFLAGS
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KASAN
export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV CFLAGS_KASAN CFLAGS_UBSAN
export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
@ -784,6 +784,7 @@ endif
include scripts/Makefile.kasan
include scripts/Makefile.extrawarn
include scripts/Makefile.ubsan
# Add any arch overrides and user supplied CPPFLAGS, AFLAGS and CFLAGS as the
# last assignments

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@ -31,6 +31,7 @@ config X86
select ARCH_HAS_PMEM_API if X86_64
select ARCH_HAS_MMIO_FLUSH
select ARCH_HAS_SG_CHAIN
select ARCH_HAS_UBSAN_SANITIZE_ALL
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
select ARCH_MIGHT_HAVE_PC_PARPORT

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@ -60,6 +60,7 @@ clean-files += cpustr.h
KBUILD_CFLAGS := $(USERINCLUDE) $(REALMODE_CFLAGS) -D_SETUP
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n
UBSAN_SANITIZE := n
$(obj)/bzImage: asflags-y := $(SVGA_MODE)

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@ -33,6 +33,7 @@ KBUILD_CFLAGS += $(call cc-option,-fno-stack-protector)
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n
UBSAN_SANITIZE :=n
LDFLAGS := -m elf_$(UTS_MACHINE)
LDFLAGS_vmlinux := -T

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@ -4,6 +4,7 @@
KBUILD_CFLAGS += $(DISABLE_LTO)
KASAN_SANITIZE := n
UBSAN_SANITIZE := n
VDSO64-$(CONFIG_X86_64) := y
VDSOX32-$(CONFIG_X86_X32_ABI) := y

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@ -70,3 +70,4 @@ KBUILD_CFLAGS := $(LINUXINCLUDE) $(REALMODE_CFLAGS) -D_SETUP -D_WAKEUP \
-I$(srctree)/arch/x86/boot
KBUILD_AFLAGS := $(KBUILD_CFLAGS) -D__ASSEMBLY__
GCOV_PROFILE := n
UBSAN_SANITIZE := n

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@ -22,6 +22,7 @@ KBUILD_CFLAGS := $(cflags-y) -DDISABLE_BRANCH_PROFILING \
GCOV_PROFILE := n
KASAN_SANITIZE := n
UBSAN_SANITIZE := n
lib-y := efi-stub-helper.o

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@ -1643,6 +1643,9 @@ struct task_struct {
struct held_lock held_locks[MAX_LOCK_DEPTH];
gfp_t lockdep_reclaim_gfp;
#endif
#ifdef CONFIG_UBSAN
unsigned int in_ubsan;
#endif
/* journalling filesystem info */
void *journal_info;

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@ -1893,6 +1893,8 @@ source "samples/Kconfig"
source "lib/Kconfig.kgdb"
source "lib/Kconfig.ubsan"
config ARCH_HAS_DEVMEM_IS_ALLOWED
bool

29
lib/Kconfig.ubsan Normal file
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@ -0,0 +1,29 @@
config ARCH_HAS_UBSAN_SANITIZE_ALL
bool
config UBSAN
bool "Undefined behaviour sanity checker"
help
This option enables undefined behaviour sanity checker
Compile-time instrumentation is used to detect various undefined
behaviours in runtime. Various types of checks may be enabled
via boot parameter ubsan_handle (see: Documentation/ubsan.txt).
config UBSAN_SANITIZE_ALL
bool "Enable instrumentation for the entire kernel"
depends on UBSAN
depends on ARCH_HAS_UBSAN_SANITIZE_ALL
default y
help
This option activates instrumentation for the entire kernel.
If you don't enable this option, you have to explicitly specify
UBSAN_SANITIZE := y for the files/directories you want to check for UB.
config UBSAN_ALIGNMENT
bool "Enable checking of pointers alignment"
depends on UBSAN
default y if !HAVE_EFFICIENT_UNALIGNED_ACCESS
help
This option enables detection of unaligned memory accesses.
Enabling this option on architectures that support unalligned
accesses may produce a lot of false positives.

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@ -209,3 +209,6 @@ quiet_cmd_build_OID_registry = GEN $@
clean-files += oid_registry_data.c
obj-$(CONFIG_UCS2_STRING) += ucs2_string.o
obj-$(CONFIG_UBSAN) += ubsan.o
UBSAN_SANITIZE_ubsan.o := n

456
lib/ubsan.c Normal file
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@ -0,0 +1,456 @@
/*
* UBSAN error reporting functions
*
* Copyright (c) 2014 Samsung Electronics Co., Ltd.
* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/bitops.h>
#include <linux/bug.h>
#include <linux/ctype.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/sched.h>
#include "ubsan.h"
const char *type_check_kinds[] = {
"load of",
"store to",
"reference binding to",
"member access within",
"member call on",
"constructor call on",
"downcast of",
"downcast of"
};
#define REPORTED_BIT 31
#if (BITS_PER_LONG == 64) && defined(__BIG_ENDIAN)
#define COLUMN_MASK (~(1U << REPORTED_BIT))
#define LINE_MASK (~0U)
#else
#define COLUMN_MASK (~0U)
#define LINE_MASK (~(1U << REPORTED_BIT))
#endif
#define VALUE_LENGTH 40
static bool was_reported(struct source_location *location)
{
return test_and_set_bit(REPORTED_BIT, &location->reported);
}
static void print_source_location(const char *prefix,
struct source_location *loc)
{
pr_err("%s %s:%d:%d\n", prefix, loc->file_name,
loc->line & LINE_MASK, loc->column & COLUMN_MASK);
}
static bool suppress_report(struct source_location *loc)
{
return current->in_ubsan || was_reported(loc);
}
static bool type_is_int(struct type_descriptor *type)
{
return type->type_kind == type_kind_int;
}
static bool type_is_signed(struct type_descriptor *type)
{
WARN_ON(!type_is_int(type));
return type->type_info & 1;
}
static unsigned type_bit_width(struct type_descriptor *type)
{
return 1 << (type->type_info >> 1);
}
static bool is_inline_int(struct type_descriptor *type)
{
unsigned inline_bits = sizeof(unsigned long)*8;
unsigned bits = type_bit_width(type);
WARN_ON(!type_is_int(type));
return bits <= inline_bits;
}
static s_max get_signed_val(struct type_descriptor *type, unsigned long val)
{
if (is_inline_int(type)) {
unsigned extra_bits = sizeof(s_max)*8 - type_bit_width(type);
return ((s_max)val) << extra_bits >> extra_bits;
}
if (type_bit_width(type) == 64)
return *(s64 *)val;
return *(s_max *)val;
}
static bool val_is_negative(struct type_descriptor *type, unsigned long val)
{
return type_is_signed(type) && get_signed_val(type, val) < 0;
}
static u_max get_unsigned_val(struct type_descriptor *type, unsigned long val)
{
if (is_inline_int(type))
return val;
if (type_bit_width(type) == 64)
return *(u64 *)val;
return *(u_max *)val;
}
static void val_to_string(char *str, size_t size, struct type_descriptor *type,
unsigned long value)
{
if (type_is_int(type)) {
if (type_bit_width(type) == 128) {
#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
u_max val = get_unsigned_val(type, value);
scnprintf(str, size, "0x%08x%08x%08x%08x",
(u32)(val >> 96),
(u32)(val >> 64),
(u32)(val >> 32),
(u32)(val));
#else
WARN_ON(1);
#endif
} else if (type_is_signed(type)) {
scnprintf(str, size, "%lld",
(s64)get_signed_val(type, value));
} else {
scnprintf(str, size, "%llu",
(u64)get_unsigned_val(type, value));
}
}
}
static bool location_is_valid(struct source_location *loc)
{
return loc->file_name != NULL;
}
static DEFINE_SPINLOCK(report_lock);
static void ubsan_prologue(struct source_location *location,
unsigned long *flags)
{
current->in_ubsan++;
spin_lock_irqsave(&report_lock, *flags);
pr_err("========================================"
"========================================\n");
print_source_location("UBSAN: Undefined behaviour in", location);
}
static void ubsan_epilogue(unsigned long *flags)
{
dump_stack();
pr_err("========================================"
"========================================\n");
spin_unlock_irqrestore(&report_lock, *flags);
current->in_ubsan--;
}
static void handle_overflow(struct overflow_data *data, unsigned long lhs,
unsigned long rhs, char op)
{
struct type_descriptor *type = data->type;
unsigned long flags;
char lhs_val_str[VALUE_LENGTH];
char rhs_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(lhs_val_str, sizeof(lhs_val_str), type, lhs);
val_to_string(rhs_val_str, sizeof(rhs_val_str), type, rhs);
pr_err("%s integer overflow:\n",
type_is_signed(type) ? "signed" : "unsigned");
pr_err("%s %c %s cannot be represented in type %s\n",
lhs_val_str,
op,
rhs_val_str,
type->type_name);
ubsan_epilogue(&flags);
}
void __ubsan_handle_add_overflow(struct overflow_data *data,
unsigned long lhs,
unsigned long rhs)
{
handle_overflow(data, lhs, rhs, '+');
}
EXPORT_SYMBOL(__ubsan_handle_add_overflow);
void __ubsan_handle_sub_overflow(struct overflow_data *data,
unsigned long lhs,
unsigned long rhs)
{
handle_overflow(data, lhs, rhs, '-');
}
EXPORT_SYMBOL(__ubsan_handle_sub_overflow);
void __ubsan_handle_mul_overflow(struct overflow_data *data,
unsigned long lhs,
unsigned long rhs)
{
handle_overflow(data, lhs, rhs, '*');
}
EXPORT_SYMBOL(__ubsan_handle_mul_overflow);
void __ubsan_handle_negate_overflow(struct overflow_data *data,
unsigned long old_val)
{
unsigned long flags;
char old_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(old_val_str, sizeof(old_val_str), data->type, old_val);
pr_err("negation of %s cannot be represented in type %s:\n",
old_val_str, data->type->type_name);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_negate_overflow);
void __ubsan_handle_divrem_overflow(struct overflow_data *data,
unsigned long lhs,
unsigned long rhs)
{
unsigned long flags;
char rhs_val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(rhs_val_str, sizeof(rhs_val_str), data->type, rhs);
if (type_is_signed(data->type) && get_signed_val(data->type, rhs) == -1)
pr_err("division of %s by -1 cannot be represented in type %s\n",
rhs_val_str, data->type->type_name);
else
pr_err("division by zero\n");
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_divrem_overflow);
static void handle_null_ptr_deref(struct type_mismatch_data *data)
{
unsigned long flags;
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
pr_err("%s null pointer of type %s\n",
type_check_kinds[data->type_check_kind],
data->type->type_name);
ubsan_epilogue(&flags);
}
static void handle_missaligned_access(struct type_mismatch_data *data,
unsigned long ptr)
{
unsigned long flags;
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
pr_err("%s misaligned address %p for type %s\n",
type_check_kinds[data->type_check_kind],
(void *)ptr, data->type->type_name);
pr_err("which requires %ld byte alignment\n", data->alignment);
ubsan_epilogue(&flags);
}
static void handle_object_size_mismatch(struct type_mismatch_data *data,
unsigned long ptr)
{
unsigned long flags;
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
pr_err("%s address %pk with insufficient space\n",
type_check_kinds[data->type_check_kind],
(void *) ptr);
pr_err("for an object of type %s\n", data->type->type_name);
ubsan_epilogue(&flags);
}
void __ubsan_handle_type_mismatch(struct type_mismatch_data *data,
unsigned long ptr)
{
if (!ptr)
handle_null_ptr_deref(data);
else if (data->alignment && !IS_ALIGNED(ptr, data->alignment))
handle_missaligned_access(data, ptr);
else
handle_object_size_mismatch(data, ptr);
}
EXPORT_SYMBOL(__ubsan_handle_type_mismatch);
void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
{
unsigned long flags;
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
pr_err("null pointer returned from function declared to never return null\n");
if (location_is_valid(&data->attr_location))
print_source_location("returns_nonnull attribute specified in",
&data->attr_location);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_nonnull_return);
void __ubsan_handle_vla_bound_not_positive(struct vla_bound_data *data,
unsigned long bound)
{
unsigned long flags;
char bound_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(bound_str, sizeof(bound_str), data->type, bound);
pr_err("variable length array bound value %s <= 0\n", bound_str);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_vla_bound_not_positive);
void __ubsan_handle_out_of_bounds(struct out_of_bounds_data *data,
unsigned long index)
{
unsigned long flags;
char index_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(index_str, sizeof(index_str), data->index_type, index);
pr_err("index %s is out of range for type %s\n", index_str,
data->array_type->type_name);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_out_of_bounds);
void __ubsan_handle_shift_out_of_bounds(struct shift_out_of_bounds_data *data,
unsigned long lhs, unsigned long rhs)
{
unsigned long flags;
struct type_descriptor *rhs_type = data->rhs_type;
struct type_descriptor *lhs_type = data->lhs_type;
char rhs_str[VALUE_LENGTH];
char lhs_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(rhs_str, sizeof(rhs_str), rhs_type, rhs);
val_to_string(lhs_str, sizeof(lhs_str), lhs_type, lhs);
if (val_is_negative(rhs_type, rhs))
pr_err("shift exponent %s is negative\n", rhs_str);
else if (get_unsigned_val(rhs_type, rhs) >=
type_bit_width(lhs_type))
pr_err("shift exponent %s is too large for %u-bit type %s\n",
rhs_str,
type_bit_width(lhs_type),
lhs_type->type_name);
else if (val_is_negative(lhs_type, lhs))
pr_err("left shift of negative value %s\n",
lhs_str);
else
pr_err("left shift of %s by %s places cannot be"
" represented in type %s\n",
lhs_str, rhs_str,
lhs_type->type_name);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_shift_out_of_bounds);
void __noreturn
__ubsan_handle_builtin_unreachable(struct unreachable_data *data)
{
unsigned long flags;
ubsan_prologue(&data->location, &flags);
pr_err("calling __builtin_unreachable()\n");
ubsan_epilogue(&flags);
panic("can't return from __builtin_unreachable()");
}
EXPORT_SYMBOL(__ubsan_handle_builtin_unreachable);
void __ubsan_handle_load_invalid_value(struct invalid_value_data *data,
unsigned long val)
{
unsigned long flags;
char val_str[VALUE_LENGTH];
if (suppress_report(&data->location))
return;
ubsan_prologue(&data->location, &flags);
val_to_string(val_str, sizeof(val_str), data->type, val);
pr_err("load of value %s is not a valid value for type %s\n",
val_str, data->type->type_name);
ubsan_epilogue(&flags);
}
EXPORT_SYMBOL(__ubsan_handle_load_invalid_value);

84
lib/ubsan.h Normal file
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@ -0,0 +1,84 @@
#ifndef _LIB_UBSAN_H
#define _LIB_UBSAN_H
enum {
type_kind_int = 0,
type_kind_float = 1,
type_unknown = 0xffff
};
struct type_descriptor {
u16 type_kind;
u16 type_info;
char type_name[1];
};
struct source_location {
const char *file_name;
union {
unsigned long reported;
struct {
u32 line;
u32 column;
};
};
};
struct overflow_data {
struct source_location location;
struct type_descriptor *type;
};
struct type_mismatch_data {
struct source_location location;
struct type_descriptor *type;
unsigned long alignment;
unsigned char type_check_kind;
};
struct nonnull_arg_data {
struct source_location location;
struct source_location attr_location;
int arg_index;
};
struct nonnull_return_data {
struct source_location location;
struct source_location attr_location;
};
struct vla_bound_data {
struct source_location location;
struct type_descriptor *type;
};
struct out_of_bounds_data {
struct source_location location;
struct type_descriptor *array_type;
struct type_descriptor *index_type;
};
struct shift_out_of_bounds_data {
struct source_location location;
struct type_descriptor *lhs_type;
struct type_descriptor *rhs_type;
};
struct unreachable_data {
struct source_location location;
};
struct invalid_value_data {
struct source_location location;
struct type_descriptor *type;
};
#if defined(CONFIG_ARCH_SUPPORTS_INT128) && defined(__SIZEOF_INT128__)
typedef __int128 s_max;
typedef unsigned __int128 u_max;
#else
typedef s64 s_max;
typedef u64 u_max;
#endif
#endif

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@ -1,4 +1,5 @@
KASAN_SANITIZE := n
UBSAN_SANITIZE_kasan.o := n
CFLAGS_REMOVE_kasan.o = -pg
# Function splitter causes unnecessary splits in __asan_load1/__asan_store1

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@ -130,6 +130,12 @@ _c_flags += $(if $(patsubst n%,, \
$(CFLAGS_KASAN))
endif
ifeq ($(CONFIG_UBSAN),y)
_c_flags += $(if $(patsubst n%,, \
$(UBSAN_SANITIZE_$(basetarget).o)$(UBSAN_SANITIZE)$(CONFIG_UBSAN_SANITIZE_ALL)), \
$(CFLAGS_UBSAN))
endif
# If building the kernel in a separate objtree expand all occurrences
# of -Idir to -I$(srctree)/dir except for absolute paths (starting with '/').

17
scripts/Makefile.ubsan Normal file
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@ -0,0 +1,17 @@
ifdef CONFIG_UBSAN
CFLAGS_UBSAN += $(call cc-option, -fsanitize=shift)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=integer-divide-by-zero)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=unreachable)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=vla-bound)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=null)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=signed-integer-overflow)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=bounds)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=object-size)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=returns-nonnull-attribute)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=bool)
CFLAGS_UBSAN += $(call cc-option, -fsanitize=enum)
ifdef CONFIG_UBSAN_ALIGNMENT
CFLAGS_UBSAN += $(call cc-option, -fsanitize=alignment)
endif
endif