Commit 531b014e authored by Jakub Kicinski's avatar Jakub Kicinski Committed by Daniel Borkmann

tools: bpf: make use of reallocarray

reallocarray() is a safer variant of realloc which checks for
multiplication overflow in case of array allocation.  Since it's
not available in Glibc < 2.26 import kernel's overflow.h and
add a static inline implementation when needed.  Use feature
detection to probe for existence of reallocarray.
Signed-off-by: default avatarJakub Kicinski <jakub.kicinski@netronome.com>
Reviewed-by: default avatarQuentin Monnet <quentin.monnet@netronome.com>
Reviewed-by: default avatarJiong Wang <jiong.wang@netronome.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent 8d13406c
......@@ -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
......
......@@ -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"
......
......@@ -35,6 +35,7 @@
* POSSIBILITY OF SUCH DAMAGE.
*/
#define _GNU_SOURCE
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
......@@ -66,8 +67,7 @@ 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) *
tmp = reallocarray(dd->sym_mapping, dd->sym_count + 1,
sizeof(*dd->sym_mapping));
if (!tmp) {
out:
......
......@@ -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
......
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <stdlib.h>
int main(void)
{
return !!reallocarray(NULL, 1, 1);
}
......@@ -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
/* 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 */
// 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
......@@ -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
......
......@@ -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;
......
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