[PATCH v2 2/2] UBSan: run-time undefined behavior sanity checker
From: Andrey Ryabinin
Date: Fri Nov 14 2014 - 07:51:25 EST
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 [1] (see -fsanitize=undefined
option and its suboptions).
However upcoming GCC 5.0 has more checkers implemented [2].
Article [3] has a bit more details about UBSan in the GCC.
Different kinds of checks could be enabled via boot parameter:
ubsan_handle=OEAINVBSLU.
If ubsan_handle not present in cmdline default options are used: ELNVBSLU
O - different kinds of overflows
E - negation overflow, division overflow, division by zero.
A - misaligned memory access.
I - load from/store to an object with insufficient space.
N - null argument declared with nonnull attribute,
returned null from function which never returns null, null ptr dereference.
V - variable size array with non-positive length
B - out-of-bounds accesses.
S - shifting out-of-bounds.
L - load of invalid value (value out of range for the enum type, loading other then 0/1 to bool type)
U - __builtin_unreachable() was called
[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 <a.ryabinin@xxxxxxxxxxx>
---
Documentation/ubsan.txt | 69 +++++
Makefile | 10 +-
arch/x86/Kconfig | 1 +
arch/x86/boot/Makefile | 1 +
arch/x86/boot/compressed/Makefile | 1 +
arch/x86/realmode/rm/Makefile | 1 +
arch/x86/vdso/Makefile | 2 +
drivers/firmware/efi/libstub/Makefile | 1 +
include/linux/sched.h | 3 +
lib/Kconfig.debug | 22 ++
lib/Makefile | 3 +
lib/ubsan.c | 567 ++++++++++++++++++++++++++++++++++
lib/ubsan.h | 84 +++++
scripts/Makefile.lib | 6 +
14 files changed, 770 insertions(+), 1 deletion(-)
create mode 100644 Documentation/ubsan.txt
create mode 100644 lib/ubsan.c
create mode 100644 lib/ubsan.h
diff --git a/Documentation/ubsan.txt b/Documentation/ubsan.txt
new file mode 100644
index 0000000..04d6aa6
--- /dev/null
+++ b/Documentation/ubsan.txt
@@ -0,0 +1,69 @@
+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 [1] (see -fsanitize=undefined option and its suboptions).
+Upcoming GCC 5.0 has more checkers implemented [2].
+
+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
+
+Various types of checkers may be enabled via boot parameter, e.g.:
+ ubsan_handle=OEAINVBSLU
+
+Possible options are:
+ O - different kinds of integer overflows
+ E - negation overflow, division overflow, division by zero.
+ A - misaligned memory access.
+ I - load from/store to an object with insufficient space.
+ N - passing NULL as argument declared with nonnull attribute,
+ returned null from function which never returns null,
+ null ptr dereference.
+ V - variable size array with non-positive length
+ B - out-of-bounds memory accesses
+ S - shifting out-of-bounds
+ L - load of invalid value (value out of range for the enum type,
+ loading other then 0/1 to bool type)
+ U - __builtin_unreachable() was called
+
+If ubsan_handle not present in cmdline the default options are used: ELNVBSLU.
+Additionally option 'A' (misaligned access checks) enabled by default if
+architecture doesn't support unaligned accesses.
+
+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 bc7eb6a..007e06b 100644
--- a/Makefile
+++ b/Makefile
@@ -377,6 +377,7 @@ LDFLAGS_MODULE =
CFLAGS_KERNEL =
AFLAGS_KERNEL =
CFLAGS_GCOV = -fprofile-arcs -ftest-coverage
+CFLAGS_UBSAN = $(call cc-option, -fsanitize=undefined)
# Use USERINCLUDE when you must reference the UAPI directories only.
@@ -421,7 +422,7 @@ 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
+export KBUILD_CFLAGS CFLAGS_KERNEL CFLAGS_MODULE CFLAGS_GCOV 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
@@ -670,6 +671,13 @@ endif
endif
KBUILD_CFLAGS += $(stackp-flag)
+ifdef CONFIG_UBSAN
+ ifeq ($(CFLAGS_UBSAN),)
+ $(warning Cannot use CONFIG_UBSAN: \
+ -fsanitize=undefined not supported by compiler)
+ endif
+endif
+
ifeq ($(COMPILER),clang)
KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,)
KBUILD_CPPFLAGS += $(call cc-option,-Wno-unknown-warning-option,)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index ded8a67..359d8ba 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -55,6 +55,7 @@ config X86
select HAVE_FUNCTION_TRACER
select HAVE_FUNCTION_GRAPH_TRACER
select HAVE_FUNCTION_GRAPH_FP_TEST
+ select HAVE_ARCH_UBSAN_SANTIZE_ALL
select HAVE_SYSCALL_TRACEPOINTS
select SYSCTL_EXCEPTION_TRACE
select HAVE_KVM
diff --git a/arch/x86/boot/Makefile b/arch/x86/boot/Makefile
index 5b016e2..95bf522 100644
--- a/arch/x86/boot/Makefile
+++ b/arch/x86/boot/Makefile
@@ -57,6 +57,7 @@ endif
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 704f58a..16940f8 100644
--- a/arch/x86/boot/compressed/Makefile
+++ b/arch/x86/boot/compressed/Makefile
@@ -19,6 +19,7 @@ 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/realmode/rm/Makefile b/arch/x86/realmode/rm/Makefile
index 7c0d7be..5c48444 100644
--- a/arch/x86/realmode/rm/Makefile
+++ b/arch/x86/realmode/rm/Makefile
@@ -69,3 +69,4 @@ 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/arch/x86/vdso/Makefile b/arch/x86/vdso/Makefile
index 5a4affe..3054473 100644
--- a/arch/x86/vdso/Makefile
+++ b/arch/x86/vdso/Makefile
@@ -4,6 +4,8 @@
KBUILD_CFLAGS += $(DISABLE_LTO)
+UBSAN_SANITIZE := n
+
VDSO64-$(CONFIG_X86_64) := y
VDSOX32-$(CONFIG_X86_X32_ABI) := y
VDSO32-$(CONFIG_X86_32) := y
diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
index b14bc2b..7b07624 100644
--- a/drivers/firmware/efi/libstub/Makefile
+++ b/drivers/firmware/efi/libstub/Makefile
@@ -19,6 +19,7 @@ KBUILD_CFLAGS := $(cflags-y) \
$(call cc-option,-fno-stack-protector)
GCOV_PROFILE := n
+UBSAN_SANITIZE := n
lib-y := efi-stub-helper.o
lib-$(CONFIG_EFI_ARMSTUB) += arm-stub.o fdt.o
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 5e344bb..36d0e89 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1483,6 +1483,9 @@ 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 4e35a5d..8e80d7c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -646,6 +646,28 @@ config DEBUG_SHIRQ
Drivers ought to be able to handle interrupts coming in at those
points; some don't and need to be caught.
+config HAVE_ARCH_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 HAVE_ARCH_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.
+
+
menu "Debug Lockups and Hangs"
config LOCKUP_DETECTOR
diff --git a/lib/Makefile b/lib/Makefile
index 7512dc9..d8c05c68 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -196,3 +196,6 @@ 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..d946e79
--- /dev/null
+++ b/lib/ubsan.c
@@ -0,0 +1,567 @@
+/*
+ * UBSan error reporting functions
+ *
+ * Copyright (c) 2014 Samsung Electronics Co., Ltd.
+ * Author: Andrey Ryabinin <a.ryabinin@xxxxxxxxxxx>
+ *
+ * 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"
+};
+
+enum {
+ SUM_OVERFLOW,
+ SUB_OVERFLOW,
+ MUL_OVERFLOW,
+ NEG_OVERFLOW,
+ DIVREM_OVERFLOW,
+ ALIGNMENT,
+ OBJECT_SIZE,
+ NONNULL_ARG,
+ NONNULL_RET,
+ NULL_PTR,
+ VLA_BOUND,
+ OUT_OF_BOUNDS,
+ SHIFT_OUT_OF_BOUNDS,
+ INVALID_LOAD,
+ UNREACHABLE,
+ HANDLERS_END,
+};
+
+/*
+ * By default enable everything except signed overflows and
+ * misaligned accesses
+ */
+static unsigned long ubsan_handle = GENMASK(HANDLERS_END, 0) &
+ ~(BIT_MASK(SUM_OVERFLOW) | BIT_MASK(SUB_OVERFLOW) |
+#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+ BIT_MASK(ALIGNMENT) |
+#endif
+ BIT_MASK(MUL_OVERFLOW));
+
+#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 void enable_handler(unsigned int handler)
+{
+ set_bit(handler, &ubsan_handle);
+}
+
+static bool handler_enabled(unsigned int handler)
+{
+ return test_bit(handler, &ubsan_handle);
+}
+
+static bool suppress_report(unsigned int handler, struct source_location *loc)
+{
+ return current->in_ubsan || !handler_enabled(handler)
+ || 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 (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, unsigned int handler, 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(handler, &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, SUM_OVERFLOW, '+');
+}
+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, SUB_OVERFLOW, '-');
+}
+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, MUL_OVERFLOW, '*');
+}
+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(NEG_OVERFLOW, &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(DIVREM_OVERFLOW, &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(NULL_PTR, &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(ALIGNMENT, &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(OBJECT_SIZE, &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_arg(struct nonnull_arg_data *data)
+{
+ unsigned long flags;
+
+ if (suppress_report(NONNULL_ARG, &data->location))
+ return;
+
+ ubsan_prologue(&data->location, &flags);
+
+ pr_err("null pointer passed as argument %d, declared with nonnull attribute\n",
+ data->arg_index);
+
+ if (location_is_valid(&data->attr_location))
+ print_source_location("nonnull attribute declared in ",
+ &data->attr_location);
+
+ ubsan_epilogue(&flags);
+}
+EXPORT_SYMBOL(__ubsan_handle_nonnull_arg);
+
+void __ubsan_handle_nonnull_return(struct nonnull_return_data *data)
+{
+ unsigned long flags;
+
+ if (suppress_report(NONNULL_RET, &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(VLA_BOUND, &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(OUT_OF_BOUNDS, &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(SHIFT_OUT_OF_BOUNDS, &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(UNREACHABLE, &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(INVALID_LOAD, &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);
+
+static int __init setup_ubsan_handlers(char *str)
+{
+ ubsan_handle = 0;
+
+ for (; *str; str++) {
+ switch (tolower(*str)) {
+ case 'o':
+ enable_handler(SUM_OVERFLOW);
+ enable_handler(SUB_OVERFLOW);
+ enable_handler(MUL_OVERFLOW);
+ break;
+ case 'e':
+ enable_handler(NEG_OVERFLOW);
+ enable_handler(DIVREM_OVERFLOW);
+ break;
+ case 'a':
+ enable_handler(ALIGNMENT);
+ break;
+ case 'i':
+ enable_handler(OBJECT_SIZE);
+ break;
+ case 'n':
+ enable_handler(NONNULL_ARG);
+ enable_handler(NONNULL_RET);
+ enable_handler(NULL_PTR);
+ break;
+ case 'v':
+ enable_handler(VLA_BOUND);
+ break;
+ case 'b':
+ enable_handler(OUT_OF_BOUNDS);
+ break;
+ case 's':
+ enable_handler(SHIFT_OUT_OF_BOUNDS);
+ break;
+ case 'l':
+ enable_handler(INVALID_LOAD);
+ break;
+ case 'u':
+ enable_handler(UNREACHABLE);
+ break;
+ default:
+ pr_err("skipping unknown option '%c'\n", *str);
+ break;
+ }
+ }
+
+ return 0;
+}
+
+early_param("ubsan_handle", setup_ubsan_handlers);
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/scripts/Makefile.lib b/scripts/Makefile.lib
index 54be19a..3f631b9 100644
--- a/scripts/Makefile.lib
+++ b/scripts/Makefile.lib
@@ -119,6 +119,12 @@ _c_flags += $(if $(patsubst n%,, \
$(CFLAGS_GCOV))
endif
+ifeq ($(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 '/').
--
2.1.3
--
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