* [PATCH v3 2/2] UBSAN: run-time undefined behavior sanity checker
2015-11-30 15:59 [PATCH v3 0/2] UBSAN: run-time undefined behavior sanity checker Andrey Ryabinin
2015-11-30 15:59 ` [PATCH v3 1/2] kernel: printk: specify alignment for struct printk_log Andrey Ryabinin
@ 2015-11-30 15:59 ` Andrey Ryabinin
2015-11-30 16:47 ` kbuild test robot
` (2 more replies)
1 sibling, 3 replies; 6+ messages in thread
From: Andrey Ryabinin @ 2015-11-30 15:59 UTC (permalink / raw)
To: linux-kernel
Cc: Andrey Ryabinin, Andrew Morton, Peter Zijlstra, Sasha Levin,
Randy Dunlap, Rasmus Villemoes, Jonathan Corbet, Michal Marek,
Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Yury Gribov,
Dmitry Vyukov, Konstantin Khlebnikov, Kostya Serebryany, x86,
linux-doc, linux-kbuild
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/
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
---
Documentation/ubsan.txt | 84 +++++++
Makefile | 3 +-
arch/x86/Kconfig | 1 +
arch/x86/boot/Makefile | 1 +
arch/x86/boot/compressed/Makefile | 1 +
arch/x86/entry/vdso/Makefile | 1 +
arch/x86/realmode/rm/Makefile | 1 +
drivers/firmware/efi/libstub/Makefile | 1 +
include/linux/sched.h | 3 +
lib/Kconfig.debug | 1 +
lib/Kconfig.ubsan | 29 +++
lib/Makefile | 3 +
lib/ubsan.c | 452 ++++++++++++++++++++++++++++++++++
lib/ubsan.h | 84 +++++++
mm/kasan/Makefile | 1 +
scripts/Makefile.lib | 6 +
scripts/Makefile.ubsan | 18 ++
17 files changed, 689 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ubsan.txt
create mode 100644 lib/Kconfig.ubsan
create mode 100644 lib/ubsan.c
create mode 100644 lib/ubsan.h
create mode 100644 scripts/Makefile.ubsan
diff --git a/Documentation/ubsan.txt b/Documentation/ubsan.txt
new file mode 100644
index 0000000..f58215e
--- /dev/null
+++ b/Documentation/ubsan.txt
@@ -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
diff --git a/Makefile b/Makefile
index 3a0234f..e32e96e 100644
--- a/Makefile
+++ b/Makefile
@@ -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
@@ -778,6 +778,7 @@ 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
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index db3622f..c892eb4 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -30,6 +30,7 @@ config X86
select ARCH_HAS_PMEM_API if X86_64
select ARCH_HAS_MMIO_FLUSH
select ARCH_HAS_SG_CHAIN
+ select ARCH_HAS_UBSAN_SANTIZE_ALL
select ARCH_HAVE_NMI_SAFE_CMPXCHG
select ARCH_MIGHT_HAVE_ACPI_PDC if ACPI
select ARCH_MIGHT_HAVE_PC_PARPORT
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 2ee62db..bbe1a62 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -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)
diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile
index 0a291cd..f9ce75d 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -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
diff --git a/arch/x86/entry/vdso/Makefile b/arch/x86/entry/vdso/Makefile
index 265c0ed..c854541 100644
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -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
diff --git a/arch/x86/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 2730d77..3e75fcf 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -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
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index 3c0467d..b2a172d 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -22,6 +22,7 @@ KBUILD_CFLAGS := $(cflags-y) \
GCOV_PROFILE := n
KASAN_SANITIZE := n
+UBSAN_SANITIZE := n
lib-y := efi-stub-helper.o
diff --git a/include/linux/sched.h b/include/linux/sched.h
index edad7a4..f4d2f2e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1629,6 +1629,9 @@ 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;
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 8c15b29..4bab98f 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1853,3 +1853,4 @@ source "samples/Kconfig"
source "lib/Kconfig.kgdb"
+source "lib/Kconfig.ubsan"
diff --git a/lib/Kconfig.ubsan b/lib/Kconfig.ubsan
new file mode 100644
index 0000000..3c2868b
--- /dev/null
+++ b/lib/Kconfig.ubsan
@@ -0,0 +1,29 @@
+config ARCH_HAS_UBSAN_SANTIZE_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_SANTIZE_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.
diff --git a/lib/Makefile b/lib/Makefile
index 7f1de26..e710b08 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -208,3 +208,6 @@ 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
diff --git a/lib/ubsan.c b/lib/ubsan.c
new file mode 100644
index 0000000..95b0981
--- /dev/null
+++ b/lib/ubsan.c
@@ -0,0 +1,452 @@
+/*
+ * 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)
+{
+ u_max val = get_unsigned_val(type, value);
+
+ if (type_is_int(type)) {
+ if (IS_ENABLED(CONFIG_ARCH_SUPPORTS_INT128)
+ && type_bit_width(type) == 128)
+ scnprintf(str, size, "0x%08x%08x%08x%08x",
+ (u32)(val >> 96),
+ (u32)(val >> 64),
+ (u32)(val >> 32),
+ (u32)(val));
+ 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 to 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 __ubsan_handle_builtin_unreachable(struct unreachable_data *data)
+{
+ unsigned long flags;
+
+ if (suppress_report(&data->location))
+ return;
+
+ ubsan_prologue(&data->location, &flags);
+ pr_err("calling __builtin_unreachable()\n");
+ ubsan_epilogue(&flags);
+}
+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);
diff --git a/lib/ubsan.h b/lib/ubsan.h
new file mode 100644
index 0000000..7407127
--- /dev/null
+++ b/lib/ubsan.h
@@ -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;
+};
+
+#ifdef CONFIG_ARCH_SUPPORTS_INT128
+typedef __int128 s_max;
+typedef unsigned __int128 u_max;
+#else
+typedef s64 s_max;
+typedef u64 u_max;
+#endif
+
+#endif
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile
index 6471014..a61460d 100644
--- a/mm/kasan/Makefile
+++ b/mm/kasan/Makefile
@@ -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
diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
index 79e8661..d7c2032 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -129,6 +129,12 @@ _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 '/').
diff --git a/scripts/Makefile.ubsan b/scripts/Makefile.ubsan
new file mode 100644
index 0000000..0a0b36d
--- /dev/null
+++ b/scripts/Makefile.ubsan
@@ -0,0 +1,18 @@
+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=bounds-strict)
+ 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
--
2.4.10
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