diff options
| -rw-r--r-- | tools/bpf/bpftool/Makefile | 6 | ||||
| -rw-r--r-- | tools/bpf/bpftool/main.h | 1 | ||||
| -rw-r--r-- | tools/bpf/bpftool/xlated_dumper.c | 6 | ||||
| -rw-r--r-- | tools/build/feature/Makefile | 4 | ||||
| -rw-r--r-- | tools/build/feature/test-reallocarray.c | 8 | ||||
| -rw-r--r-- | tools/include/linux/compiler-gcc.h | 4 | ||||
| -rw-r--r-- | tools/include/linux/overflow.h | 278 | ||||
| -rw-r--r-- | tools/include/tools/libc_compat.h | 20 | ||||
| -rw-r--r-- | tools/lib/bpf/Makefile | 6 | ||||
| -rw-r--r-- | tools/lib/bpf/libbpf.c | 10 |
10 files changed, 334 insertions, 9 deletions
diff --git a/tools/bpf/bpftool/Makefile b/tools/bpf/bpftool/Makefile index 0911b00b25cc..6c4830e18879 100644 --- a/tools/bpf/bpftool/Makefile +++ b/tools/bpf/bpftool/Makefile @@ -52,7 +52,7 @@ INSTALL ?= install RM ?= rm -f FEATURE_USER = .bpftool -FEATURE_TESTS = libbfd disassembler-four-args +FEATURE_TESTS = libbfd disassembler-four-args reallocarray FEATURE_DISPLAY = libbfd disassembler-four-args check_feat := 1 @@ -75,6 +75,10 @@ ifeq ($(feature-disassembler-four-args), 1) CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE endif +ifeq ($(feature-reallocarray), 0) +CFLAGS += -DCOMPAT_NEED_REALLOCARRAY +endif + include $(wildcard $(OUTPUT)*.d) all: $(OUTPUT)bpftool diff --git a/tools/bpf/bpftool/main.h b/tools/bpf/bpftool/main.h index 15b6c49ae533..1e02e4031693 100644 --- a/tools/bpf/bpftool/main.h +++ b/tools/bpf/bpftool/main.h @@ -42,6 +42,7 @@ #include <linux/compiler.h> #include <linux/kernel.h> #include <linux/hashtable.h> +#include <tools/libc_compat.h> #include "json_writer.h" diff --git a/tools/bpf/bpftool/xlated_dumper.c b/tools/bpf/bpftool/xlated_dumper.c index b97f1da60dd1..3284759df98a 100644 --- a/tools/bpf/bpftool/xlated_dumper.c +++ b/tools/bpf/bpftool/xlated_dumper.c @@ -35,6 +35,7 @@ * POSSIBILITY OF SUCH DAMAGE. */ +#define _GNU_SOURCE #include <stdarg.h> #include <stdio.h> #include <stdlib.h> @@ -66,9 +67,8 @@ void kernel_syms_load(struct dump_data *dd) while (!feof(fp)) { if (!fgets(buff, sizeof(buff), fp)) break; - tmp = realloc(dd->sym_mapping, - (dd->sym_count + 1) * - sizeof(*dd->sym_mapping)); + tmp = reallocarray(dd->sym_mapping, dd->sym_count + 1, + sizeof(*dd->sym_mapping)); if (!tmp) { out: free(dd->sym_mapping); diff --git a/tools/build/feature/Makefile b/tools/build/feature/Makefile index dac9563b5470..0516259be70f 100644 --- a/tools/build/feature/Makefile +++ b/tools/build/feature/Makefile @@ -14,6 +14,7 @@ FILES= \ test-libaudit.bin \ test-libbfd.bin \ test-disassembler-four-args.bin \ + test-reallocarray.bin \ test-liberty.bin \ test-liberty-z.bin \ test-cplus-demangle.bin \ @@ -204,6 +205,9 @@ $(OUTPUT)test-libbfd.bin: $(OUTPUT)test-disassembler-four-args.bin: $(BUILD) -DPACKAGE='"perf"' -lbfd -lopcodes +$(OUTPUT)test-reallocarray.bin: + $(BUILD) + $(OUTPUT)test-liberty.bin: $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty diff --git a/tools/build/feature/test-reallocarray.c b/tools/build/feature/test-reallocarray.c new file mode 100644 index 000000000000..8170de35150d --- /dev/null +++ b/tools/build/feature/test-reallocarray.c @@ -0,0 +1,8 @@ +// SPDX-License-Identifier: GPL-2.0 +#define _GNU_SOURCE +#include <stdlib.h> + +int main(void) +{ + return !!reallocarray(NULL, 1, 1); +} diff --git a/tools/include/linux/compiler-gcc.h b/tools/include/linux/compiler-gcc.h index 70fe61295733..0d35f18006a1 100644 --- a/tools/include/linux/compiler-gcc.h +++ b/tools/include/linux/compiler-gcc.h @@ -36,3 +36,7 @@ #endif #define __printf(a, b) __attribute__((format(printf, a, b))) #define __scanf(a, b) __attribute__((format(scanf, a, b))) + +#if GCC_VERSION >= 50100 +#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1 +#endif diff --git a/tools/include/linux/overflow.h b/tools/include/linux/overflow.h new file mode 100644 index 000000000000..8712ff70995f --- /dev/null +++ b/tools/include/linux/overflow.h @@ -0,0 +1,278 @@ +/* SPDX-License-Identifier: GPL-2.0 OR MIT */ +#ifndef __LINUX_OVERFLOW_H +#define __LINUX_OVERFLOW_H + +#include <linux/compiler.h> + +/* + * In the fallback code below, we need to compute the minimum and + * maximum values representable in a given type. These macros may also + * be useful elsewhere, so we provide them outside the + * COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW block. + * + * It would seem more obvious to do something like + * + * #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0) + * #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0) + * + * Unfortunately, the middle expressions, strictly speaking, have + * undefined behaviour, and at least some versions of gcc warn about + * the type_max expression (but not if -fsanitize=undefined is in + * effect; in that case, the warning is deferred to runtime...). + * + * The slightly excessive casting in type_min is to make sure the + * macros also produce sensible values for the exotic type _Bool. [The + * overflow checkers only almost work for _Bool, but that's + * a-feature-not-a-bug, since people shouldn't be doing arithmetic on + * _Bools. Besides, the gcc builtins don't allow _Bool* as third + * argument.] + * + * Idea stolen from + * https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html - + * credit to Christian Biere. + */ +#define is_signed_type(type) (((type)(-1)) < (type)1) +#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type))) +#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T))) +#define type_min(T) ((T)((T)-type_max(T)-(T)1)) + + +#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW +/* + * For simplicity and code hygiene, the fallback code below insists on + * a, b and *d having the same type (similar to the min() and max() + * macros), whereas gcc's type-generic overflow checkers accept + * different types. Hence we don't just make check_add_overflow an + * alias for __builtin_add_overflow, but add type checks similar to + * below. + */ +#define check_add_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + __builtin_add_overflow(__a, __b, __d); \ +}) + +#define check_sub_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + __builtin_sub_overflow(__a, __b, __d); \ +}) + +#define check_mul_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + __builtin_mul_overflow(__a, __b, __d); \ +}) + +#else + + +/* Checking for unsigned overflow is relatively easy without causing UB. */ +#define __unsigned_add_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = __a + __b; \ + *__d < __a; \ +}) +#define __unsigned_sub_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = __a - __b; \ + __a < __b; \ +}) +/* + * If one of a or b is a compile-time constant, this avoids a division. + */ +#define __unsigned_mul_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = __a * __b; \ + __builtin_constant_p(__b) ? \ + __b > 0 && __a > type_max(typeof(__a)) / __b : \ + __a > 0 && __b > type_max(typeof(__b)) / __a; \ +}) + +/* + * For signed types, detecting overflow is much harder, especially if + * we want to avoid UB. But the interface of these macros is such that + * we must provide a result in *d, and in fact we must produce the + * result promised by gcc's builtins, which is simply the possibly + * wrapped-around value. Fortunately, we can just formally do the + * operations in the widest relevant unsigned type (u64) and then + * truncate the result - gcc is smart enough to generate the same code + * with and without the (u64) casts. + */ + +/* + * Adding two signed integers can overflow only if they have the same + * sign, and overflow has happened iff the result has the opposite + * sign. + */ +#define __signed_add_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = (u64)__a + (u64)__b; \ + (((~(__a ^ __b)) & (*__d ^ __a)) \ + & type_min(typeof(__a))) != 0; \ +}) + +/* + * Subtraction is similar, except that overflow can now happen only + * when the signs are opposite. In this case, overflow has happened if + * the result has the opposite sign of a. + */ +#define __signed_sub_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = (u64)__a - (u64)__b; \ + ((((__a ^ __b)) & (*__d ^ __a)) \ + & type_min(typeof(__a))) != 0; \ +}) + +/* + * Signed multiplication is rather hard. gcc always follows C99, so + * division is truncated towards 0. This means that we can write the + * overflow check like this: + * + * (a > 0 && (b > MAX/a || b < MIN/a)) || + * (a < -1 && (b > MIN/a || b < MAX/a) || + * (a == -1 && b == MIN) + * + * The redundant casts of -1 are to silence an annoying -Wtype-limits + * (included in -Wextra) warning: When the type is u8 or u16, the + * __b_c_e in check_mul_overflow obviously selects + * __unsigned_mul_overflow, but unfortunately gcc still parses this + * code and warns about the limited range of __b. + */ + +#define __signed_mul_overflow(a, b, d) ({ \ + typeof(a) __a = (a); \ + typeof(b) __b = (b); \ + typeof(d) __d = (d); \ + typeof(a) __tmax = type_max(typeof(a)); \ + typeof(a) __tmin = type_min(typeof(a)); \ + (void) (&__a == &__b); \ + (void) (&__a == __d); \ + *__d = (u64)__a * (u64)__b; \ + (__b > 0 && (__a > __tmax/__b || __a < __tmin/__b)) || \ + (__b < (typeof(__b))-1 && (__a > __tmin/__b || __a < __tmax/__b)) || \ + (__b == (typeof(__b))-1 && __a == __tmin); \ +}) + + +#define check_add_overflow(a, b, d) \ + __builtin_choose_expr(is_signed_type(typeof(a)), \ + __signed_add_overflow(a, b, d), \ + __unsigned_add_overflow(a, b, d)) + +#define check_sub_overflow(a, b, d) \ + __builtin_choose_expr(is_signed_type(typeof(a)), \ + __signed_sub_overflow(a, b, d), \ + __unsigned_sub_overflow(a, b, d)) + +#define check_mul_overflow(a, b, d) \ + __builtin_choose_expr(is_signed_type(typeof(a)), \ + __signed_mul_overflow(a, b, d), \ + __unsigned_mul_overflow(a, b, d)) + + +#endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */ + +/** + * array_size() - Calculate size of 2-dimensional array. + * + * @a: dimension one + * @b: dimension two + * + * Calculates size of 2-dimensional array: @a * @b. + * + * Returns: number of bytes needed to represent the array or SIZE_MAX on + * overflow. + */ +static inline __must_check size_t array_size(size_t a, size_t b) +{ + size_t bytes; + + if (check_mul_overflow(a, b, &bytes)) + return SIZE_MAX; + + return bytes; +} + +/** + * array3_size() - Calculate size of 3-dimensional array. + * + * @a: dimension one + * @b: dimension two + * @c: dimension three + * + * Calculates size of 3-dimensional array: @a * @b * @c. + * + * Returns: number of bytes needed to represent the array or SIZE_MAX on + * overflow. + */ +static inline __must_check size_t array3_size(size_t a, size_t b, size_t c) +{ + size_t bytes; + + if (check_mul_overflow(a, b, &bytes)) + return SIZE_MAX; + if (check_mul_overflow(bytes, c, &bytes)) + return SIZE_MAX; + + return bytes; +} + +static inline __must_check size_t __ab_c_size(size_t n, size_t size, size_t c) +{ + size_t bytes; + + if (check_mul_overflow(n, size, &bytes)) + return SIZE_MAX; + if (check_add_overflow(bytes, c, &bytes)) + return SIZE_MAX; + + return bytes; +} + +/** + * struct_size() - Calculate size of structure with trailing array. + * @p: Pointer to the structure. + * @member: Name of the array member. + * @n: Number of elements in the array. + * + * Calculates size of memory needed for structure @p followed by an + * array of @n @member elements. + * + * Return: number of bytes needed or SIZE_MAX on overflow. + */ +#define struct_size(p, member, n) \ + __ab_c_size(n, \ + sizeof(*(p)->member) + __must_be_array((p)->member),\ + sizeof(*(p))) + +#endif /* __LINUX_OVERFLOW_H */ diff --git a/tools/include/tools/libc_compat.h b/tools/include/tools/libc_compat.h new file mode 100644 index 000000000000..664ced8cb1b0 --- /dev/null +++ b/tools/include/tools/libc_compat.h @@ -0,0 +1,20 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* Copyright (C) 2018 Netronome Systems, Inc. */ + +#ifndef __TOOLS_LIBC_COMPAT_H +#define __TOOLS_LIBC_COMPAT_H + +#include <stdlib.h> +#include <linux/overflow.h> + +#ifdef COMPAT_NEED_REALLOCARRAY +static inline void *reallocarray(void *ptr, size_t nmemb, size_t size) +{ + size_t bytes; + + if (unlikely(check_mul_overflow(nmemb, size, &bytes))) + return NULL; + return realloc(ptr, bytes); +} +#endif +#endif diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile index 5390e7725e43..7a8e4c98ef1a 100644 --- a/tools/lib/bpf/Makefile +++ b/tools/lib/bpf/Makefile @@ -66,7 +66,7 @@ ifndef VERBOSE endif FEATURE_USER = .libbpf -FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf +FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf reallocarray FEATURE_DISPLAY = libelf bpf INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi -I$(srctree)/tools/perf @@ -120,6 +120,10 @@ ifeq ($(feature-libelf-getphdrnum), 1) override CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT endif +ifeq ($(feature-reallocarray), 0) + override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY +endif + # Append required CFLAGS override CFLAGS += $(EXTRA_WARNINGS) override CFLAGS += -Werror -Wall diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index f732237610e5..fd2c4433863d 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -22,6 +22,7 @@ * License along with this program; if not, see <http://www.gnu.org/licenses> */ +#define _GNU_SOURCE #include <stdlib.h> #include <stdio.h> #include <stdarg.h> @@ -41,6 +42,7 @@ #include <sys/stat.h> #include <sys/types.h> #include <sys/vfs.h> +#include <tools/libc_compat.h> #include <libelf.h> #include <gelf.h> @@ -321,7 +323,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size, progs = obj->programs; nr_progs = obj->nr_programs; - progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1)); + progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0])); if (!progs) { /* * In this case the original obj->programs @@ -822,8 +824,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj) continue; } - reloc = realloc(reloc, - sizeof(*obj->efile.reloc) * nr_reloc); + reloc = reallocarray(reloc, nr_reloc, + sizeof(*obj->efile.reloc)); if (!reloc) { pr_warning("realloc failed\n"); err = -ENOMEM; @@ -1115,7 +1117,7 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj, return -LIBBPF_ERRNO__RELOC; } new_cnt = prog->insns_cnt + text->insns_cnt; - new_insn = realloc(prog->insns, new_cnt * sizeof(*insn)); + new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn)); if (!new_insn) { pr_warning("oom in prog realloc\n"); return -ENOMEM; |