History

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.

Jakub Kicinski committed 8 years ago

Commit 531b0141 parent 8d1340610 files · +334 −9Browse files

Unified · Split

10 files
  1. tools/bpf/bpftool/Makefile +5 −1
  2. tools/bpf/bpftool/main.h +1 −0
  3. tools/bpf/bpftool/xlated_dumper.c +3 −3
  4. tools/build/feature/Makefile +4 −0
  5. tools/build/feature/test-reallocarray.c +8 −0
  6. tools/include/linux/compiler-gcc.h +4 −0
  7. tools/include/linux/overflow.h +278 −0
  8. tools/include/tools/libc_compat.h +20 −0
  9. tools/lib/bpf/Makefile +5 −1
  10. tools/lib/bpf/libbpf.c +6 −4
tools/bpf/bpftool/Makefile+5−1
@@ -52,7 +52,7 @@ INSTALL ?= install · 51 unmodified lines
52RM ?= rm -f52RM ?= rm -f
53 53
54FEATURE_USER = .bpftool54FEATURE_USER = .bpftool
55FEATURE_TESTS = libbfd disassembler-four-args55FEATURE_TESTS = libbfd disassembler-four-args reallocarray
56FEATURE_DISPLAY = libbfd disassembler-four-args56FEATURE_DISPLAY = libbfd disassembler-four-args
57 57
58check_feat := 158check_feat := 1
@@ -75,6 +75,10 @@ ifeq ($(feature-disassembler-four-args), 1) · 16 unmodified lines
75CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE75CFLAGS += -DDISASM_FOUR_ARGS_SIGNATURE
76endif76endif
77 77
78ifeq ($(feature-reallocarray), 0)
79CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
80endif
81
78include $(wildcard $(OUTPUT)*.d)82include $(wildcard $(OUTPUT)*.d)
79 83
80all: $(OUTPUT)bpftool84all: $(OUTPUT)bpftool
tools/bpf/bpftool/main.h+1−0
@@ -42,6 +42,7 @@ · 41 unmodified lines
42#include <linux/compiler.h>42#include <linux/compiler.h>
43#include <linux/kernel.h>43#include <linux/kernel.h>
44#include <linux/hashtable.h>44#include <linux/hashtable.h>
45#include <tools/libc_compat.h>
45 46
46#include "json_writer.h"47#include "json_writer.h"
47 48
tools/bpf/bpftool/xlated_dumper.c+3−3
@@ -35,6 +35,7 @@ · 34 unmodified lines
35 * POSSIBILITY OF SUCH DAMAGE.35 * POSSIBILITY OF SUCH DAMAGE.
36 */36 */
37 37
38#define _GNU_SOURCE
38#include <stdarg.h>39#include <stdarg.h>
39#include <stdio.h>40#include <stdio.h>
40#include <stdlib.h>41#include <stdlib.h>
@@ -66,9 +67,8 @@ void kernel_syms_load(struct dump_data *dd) · 25 unmodified lines
66 while (!feof(fp)) {67 while (!feof(fp)) {
67 if (!fgets(buff, sizeof(buff), fp))68 if (!fgets(buff, sizeof(buff), fp))
68 break;69 break;
69 tmp = realloc(dd->sym_mapping,70 tmp = reallocarray(dd->sym_mapping, dd->sym_count + 1,
70 (dd->sym_count + 1) *71 sizeof(*dd->sym_mapping));
71 sizeof(*dd->sym_mapping));
72 if (!tmp) {72 if (!tmp) {
73out:73out:
74 free(dd->sym_mapping);74 free(dd->sym_mapping);
tools/build/feature/Makefile+4−0
@@ -14,6 +14,7 @@ FILES= \ · 13 unmodified lines
14 test-libaudit.bin \14 test-libaudit.bin \
15 test-libbfd.bin \15 test-libbfd.bin \
16 test-disassembler-four-args.bin \16 test-disassembler-four-args.bin \
17 test-reallocarray.bin \
17 test-liberty.bin \18 test-liberty.bin \
18 test-liberty-z.bin \19 test-liberty-z.bin \
19 test-cplus-demangle.bin \20 test-cplus-demangle.bin \
@@ -204,6 +205,9 @@ $(OUTPUT)test-libbfd.bin: · 184 unmodified lines
204$(OUTPUT)test-disassembler-four-args.bin:205$(OUTPUT)test-disassembler-four-args.bin:
205 $(BUILD) -DPACKAGE='"perf"' -lbfd -lopcodes206 $(BUILD) -DPACKAGE='"perf"' -lbfd -lopcodes
206 207
208$(OUTPUT)test-reallocarray.bin:
209 $(BUILD)
210
207$(OUTPUT)test-liberty.bin:211$(OUTPUT)test-liberty.bin:
208 $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty212 $(CC) $(CFLAGS) -Wall -Werror -o $@ test-libbfd.c -DPACKAGE='"perf"' $(LDFLAGS) -lbfd -ldl -liberty
209 213
tools/build/feature/test-reallocarray.c+8−0
@@ -0,0 +1,8 @@
1// SPDX-License-Identifier: GPL-2.0
2#define _GNU_SOURCE
3#include <stdlib.h>
4
5int main(void)
6{
7 return !!reallocarray(NULL, 1, 1);
8}
tools/include/linux/compiler-gcc.h+4−0
@@ -36,3 +36,7 @@ · 35 unmodified lines
36#endif36#endif
37#define __printf(a, b) __attribute__((format(printf, a, b)))37#define __printf(a, b) __attribute__((format(printf, a, b)))
38#define __scanf(a, b) __attribute__((format(scanf, a, b)))38#define __scanf(a, b) __attribute__((format(scanf, a, b)))
39
40#if GCC_VERSION >= 50100
41#define COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW 1
42#endif
tools/include/linux/overflow.h+278−0
@@ -0,0 +1,278 @@
1/* SPDX-License-Identifier: GPL-2.0 OR MIT */
2#ifndef __LINUX_OVERFLOW_H
3#define __LINUX_OVERFLOW_H
4
5#include <linux/compiler.h>
6
7/*
8 * In the fallback code below, we need to compute the minimum and
9 * maximum values representable in a given type. These macros may also
10 * be useful elsewhere, so we provide them outside the
11 * COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW block.
12 *
13 * It would seem more obvious to do something like
14 *
15 * #define type_min(T) (T)(is_signed_type(T) ? (T)1 << (8*sizeof(T)-1) : 0)
16 * #define type_max(T) (T)(is_signed_type(T) ? ((T)1 << (8*sizeof(T)-1)) - 1 : ~(T)0)
17 *
18 * Unfortunately, the middle expressions, strictly speaking, have
19 * undefined behaviour, and at least some versions of gcc warn about
20 * the type_max expression (but not if -fsanitize=undefined is in
21 * effect; in that case, the warning is deferred to runtime...).
22 *
23 * The slightly excessive casting in type_min is to make sure the
24 * macros also produce sensible values for the exotic type _Bool. [The
25 * overflow checkers only almost work for _Bool, but that's
26 * a-feature-not-a-bug, since people shouldn't be doing arithmetic on
27 * _Bools. Besides, the gcc builtins don't allow _Bool* as third
28 * argument.]
29 *
30 * Idea stolen from
31 * https://mail-index.netbsd.org/tech-misc/2007/02/05/0000.html -
32 * credit to Christian Biere.
33 */
34#define is_signed_type(type) (((type)(-1)) < (type)1)
35#define __type_half_max(type) ((type)1 << (8*sizeof(type) - 1 - is_signed_type(type)))
36#define type_max(T) ((T)((__type_half_max(T) - 1) + __type_half_max(T)))
37#define type_min(T) ((T)((T)-type_max(T)-(T)1))
38
39
40#ifdef COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW
41/*
42 * For simplicity and code hygiene, the fallback code below insists on
43 * a, b and *d having the same type (similar to the min() and max()
44 * macros), whereas gcc's type-generic overflow checkers accept
45 * different types. Hence we don't just make check_add_overflow an
46 * alias for __builtin_add_overflow, but add type checks similar to
47 * below.
48 */
49#define check_add_overflow(a, b, d) ({ \
50 typeof(a) __a = (a); \
51 typeof(b) __b = (b); \
52 typeof(d) __d = (d); \
53 (void) (&__a == &__b); \
54 (void) (&__a == __d); \
55 __builtin_add_overflow(__a, __b, __d); \
56})
57
58#define check_sub_overflow(a, b, d) ({ \
59 typeof(a) __a = (a); \
60 typeof(b) __b = (b); \
61 typeof(d) __d = (d); \
62 (void) (&__a == &__b); \
63 (void) (&__a == __d); \
64 __builtin_sub_overflow(__a, __b, __d); \
65})
66
67#define check_mul_overflow(a, b, d) ({ \
68 typeof(a) __a = (a); \
69 typeof(b) __b = (b); \
70 typeof(d) __d = (d); \
71 (void) (&__a == &__b); \
72 (void) (&__a == __d); \
73 __builtin_mul_overflow(__a, __b, __d); \
74})
75
76#else
77
78
79/* Checking for unsigned overflow is relatively easy without causing UB. */
80#define __unsigned_add_overflow(a, b, d) ({ \
81 typeof(a) __a = (a); \
82 typeof(b) __b = (b); \
83 typeof(d) __d = (d); \
84 (void) (&__a == &__b); \
85 (void) (&__a == __d); \
86 *__d = __a + __b; \
87 *__d < __a; \
88})
89#define __unsigned_sub_overflow(a, b, d) ({ \
90 typeof(a) __a = (a); \
91 typeof(b) __b = (b); \
92 typeof(d) __d = (d); \
93 (void) (&__a == &__b); \
94 (void) (&__a == __d); \
95 *__d = __a - __b; \
96 __a < __b; \
97})
98/*
99 * If one of a or b is a compile-time constant, this avoids a division.
100 */
101#define __unsigned_mul_overflow(a, b, d) ({ \
102 typeof(a) __a = (a); \
103 typeof(b) __b = (b); \
104 typeof(d) __d = (d); \
105 (void) (&__a == &__b); \
106 (void) (&__a == __d); \
107 *__d = __a * __b; \
108 __builtin_constant_p(__b) ? \
109 __b > 0 && __a > type_max(typeof(__a)) / __b : \
110 __a > 0 && __b > type_max(typeof(__b)) / __a; \
111})
112
113/*
114 * For signed types, detecting overflow is much harder, especially if
115 * we want to avoid UB. But the interface of these macros is such that
116 * we must provide a result in *d, and in fact we must produce the
117 * result promised by gcc's builtins, which is simply the possibly
118 * wrapped-around value. Fortunately, we can just formally do the
119 * operations in the widest relevant unsigned type (u64) and then
120 * truncate the result - gcc is smart enough to generate the same code
121 * with and without the (u64) casts.
122 */
123
124/*
125 * Adding two signed integers can overflow only if they have the same
126 * sign, and overflow has happened iff the result has the opposite
127 * sign.
128 */
129#define __signed_add_overflow(a, b, d) ({ \
130 typeof(a) __a = (a); \
131 typeof(b) __b = (b); \
132 typeof(d) __d = (d); \
133 (void) (&__a == &__b); \
134 (void) (&__a == __d); \
135 *__d = (u64)__a + (u64)__b; \
136 (((~(__a ^ __b)) & (*__d ^ __a)) \
137 & type_min(typeof(__a))) != 0; \
138})
139
140/*
141 * Subtraction is similar, except that overflow can now happen only
142 * when the signs are opposite. In this case, overflow has happened if
143 * the result has the opposite sign of a.
144 */
145#define __signed_sub_overflow(a, b, d) ({ \
146 typeof(a) __a = (a); \
147 typeof(b) __b = (b); \
148 typeof(d) __d = (d); \
149 (void) (&__a == &__b); \
150 (void) (&__a == __d); \
151 *__d = (u64)__a - (u64)__b; \
152 ((((__a ^ __b)) & (*__d ^ __a)) \
153 & type_min(typeof(__a))) != 0; \
154})
155
156/*
157 * Signed multiplication is rather hard. gcc always follows C99, so
158 * division is truncated towards 0. This means that we can write the
159 * overflow check like this:
160 *
161 * (a > 0 && (b > MAX/a || b < MIN/a)) ||
162 * (a < -1 && (b > MIN/a || b < MAX/a) ||
163 * (a == -1 && b == MIN)
164 *
165 * The redundant casts of -1 are to silence an annoying -Wtype-limits
166 * (included in -Wextra) warning: When the type is u8 or u16, the
167 * __b_c_e in check_mul_overflow obviously selects
168 * __unsigned_mul_overflow, but unfortunately gcc still parses this
169 * code and warns about the limited range of __b.
170 */
171
172#define __signed_mul_overflow(a, b, d) ({ \
173 typeof(a) __a = (a); \
174 typeof(b) __b = (b); \
175 typeof(d) __d = (d); \
176 typeof(a) __tmax = type_max(typeof(a)); \
177 typeof(a) __tmin = type_min(typeof(a)); \
178 (void) (&__a == &__b); \
179 (void) (&__a == __d); \
180 *__d = (u64)__a * (u64)__b; \
181 (__b > 0 && (__a > __tmax/__b || __a < __tmin/__b)) || \
182 (__b < (typeof(__b))-1 && (__a > __tmin/__b || __a < __tmax/__b)) || \
183 (__b == (typeof(__b))-1 && __a == __tmin); \
184})
185
186
187#define check_add_overflow(a, b, d) \
188 __builtin_choose_expr(is_signed_type(typeof(a)), \
189 __signed_add_overflow(a, b, d), \
190 __unsigned_add_overflow(a, b, d))
191
192#define check_sub_overflow(a, b, d) \
193 __builtin_choose_expr(is_signed_type(typeof(a)), \
194 __signed_sub_overflow(a, b, d), \
195 __unsigned_sub_overflow(a, b, d))
196
197#define check_mul_overflow(a, b, d) \
198 __builtin_choose_expr(is_signed_type(typeof(a)), \
199 __signed_mul_overflow(a, b, d), \
200 __unsigned_mul_overflow(a, b, d))
201
202
203#endif /* COMPILER_HAS_GENERIC_BUILTIN_OVERFLOW */
204
205/**
206 * array_size() - Calculate size of 2-dimensional array.
207 *
208 * @a: dimension one
209 * @b: dimension two
210 *
211 * Calculates size of 2-dimensional array: @a * @b.
212 *
213 * Returns: number of bytes needed to represent the array or SIZE_MAX on
214 * overflow.
215 */
216static inline __must_check size_t array_size(size_t a, size_t b)
217{
218 size_t bytes;
219
220 if (check_mul_overflow(a, b, &bytes))
221 return SIZE_MAX;
222
223 return bytes;
224}
225
226/**
227 * array3_size() - Calculate size of 3-dimensional array.
228 *
229 * @a: dimension one
230 * @b: dimension two
231 * @c: dimension three
232 *
233 * Calculates size of 3-dimensional array: @a * @b * @c.
234 *
235 * Returns: number of bytes needed to represent the array or SIZE_MAX on
236 * overflow.
237 */
238static inline __must_check size_t array3_size(size_t a, size_t b, size_t c)
239{
240 size_t bytes;
241
242 if (check_mul_overflow(a, b, &bytes))
243 return SIZE_MAX;
244 if (check_mul_overflow(bytes, c, &bytes))
245 return SIZE_MAX;
246
247 return bytes;
248}
249
250static inline __must_check size_t __ab_c_size(size_t n, size_t size, size_t c)
251{
252 size_t bytes;
253
254 if (check_mul_overflow(n, size, &bytes))
255 return SIZE_MAX;
256 if (check_add_overflow(bytes, c, &bytes))
257 return SIZE_MAX;
258
259 return bytes;
260}
261
262/**
263 * struct_size() - Calculate size of structure with trailing array.
264 * @p: Pointer to the structure.
265 * @member: Name of the array member.
266 * @n: Number of elements in the array.
267 *
268 * Calculates size of memory needed for structure @p followed by an
269 * array of @n @member elements.
270 *
271 * Return: number of bytes needed or SIZE_MAX on overflow.
272 */
273#define struct_size(p, member, n) \
274 __ab_c_size(n, \
275 sizeof(*(p)->member) + __must_be_array((p)->member),\
276 sizeof(*(p)))
277
278#endif /* __LINUX_OVERFLOW_H */
tools/include/tools/libc_compat.h+20−0
@@ -0,0 +1,20 @@
1// SPDX-License-Identifier: GPL-2.0+
2/* Copyright (C) 2018 Netronome Systems, Inc. */
3
4#ifndef __TOOLS_LIBC_COMPAT_H
5#define __TOOLS_LIBC_COMPAT_H
6
7#include <stdlib.h>
8#include <linux/overflow.h>
9
10#ifdef COMPAT_NEED_REALLOCARRAY
11static inline void *reallocarray(void *ptr, size_t nmemb, size_t size)
12{
13 size_t bytes;
14
15 if (unlikely(check_mul_overflow(nmemb, size, &bytes)))
16 return NULL;
17 return realloc(ptr, bytes);
18}
19#endif
20#endif
tools/lib/bpf/Makefile+5−1
@@ -66,7 +66,7 @@ ifndef VERBOSE · 65 unmodified lines
66endif66endif
67 67
68FEATURE_USER = .libbpf68FEATURE_USER = .libbpf
69FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf69FEATURE_TESTS = libelf libelf-getphdrnum libelf-mmap bpf reallocarray
70FEATURE_DISPLAY = libelf bpf70FEATURE_DISPLAY = libelf bpf
71 71
72INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi -I$(srctree)/tools/perf72INCLUDES = -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) · 47 unmodified lines
120 override CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT120 override CFLAGS += -DHAVE_ELF_GETPHDRNUM_SUPPORT
121endif121endif
122 122
123ifeq ($(feature-reallocarray), 0)
124 override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
125endif
126
123# Append required CFLAGS127# Append required CFLAGS
124override CFLAGS += $(EXTRA_WARNINGS)128override CFLAGS += $(EXTRA_WARNINGS)
125override CFLAGS += -Werror -Wall129override CFLAGS += -Werror -Wall
tools/lib/bpf/libbpf.c+6−4
@@ -22,6 +22,7 @@ · 21 unmodified lines
22 * License along with this program; if not, see <http://www.gnu.org/licenses>22 * License along with this program; if not, see <http://www.gnu.org/licenses>
23 */23 */
24 24
25#define _GNU_SOURCE
25#include <stdlib.h>26#include <stdlib.h>
26#include <stdio.h>27#include <stdio.h>
27#include <stdarg.h>28#include <stdarg.h>
@@ -41,6 +42,7 @@ · 13 unmodified lines
41#include <sys/stat.h>42#include <sys/stat.h>
42#include <sys/types.h>43#include <sys/types.h>
43#include <sys/vfs.h>44#include <sys/vfs.h>
45#include <tools/libc_compat.h>
44#include <libelf.h>46#include <libelf.h>
45#include <gelf.h>47#include <gelf.h>
46 48
@@ -321,7 +323,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size, · 274 unmodified lines
321 progs = obj->programs;323 progs = obj->programs;
322 nr_progs = obj->nr_programs;324 nr_progs = obj->nr_programs;
323 325
324 progs = realloc(progs, sizeof(progs[0]) * (nr_progs + 1));326 progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
325 if (!progs) {327 if (!progs) {
326 /*328 /*
327 * In this case the original obj->programs329 * In this case the original obj->programs
@@ -822,8 +824,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj) · 494 unmodified lines
822 continue;824 continue;
823 }825 }
824 826
825 reloc = realloc(reloc,827 reloc = reallocarray(reloc, nr_reloc,
826 sizeof(*obj->efile.reloc) * nr_reloc);828 sizeof(*obj->efile.reloc));
827 if (!reloc) {829 if (!reloc) {
828 pr_warning("realloc failed\n");830 pr_warning("realloc failed\n");
829 err = -ENOMEM;831 err = -ENOMEM;
@@ -1115,7 +1117,7 @@ bpf_program__reloc_text(struct bpf_program *prog, struct bpf_object *obj, · 285 unmodified lines
1115 return -LIBBPF_ERRNO__RELOC;1117 return -LIBBPF_ERRNO__RELOC;
1116 }1118 }
1117 new_cnt = prog->insns_cnt + text->insns_cnt;1119 new_cnt = prog->insns_cnt + text->insns_cnt;
1118 new_insn = realloc(prog->insns, new_cnt * sizeof(*insn));1120 new_insn = reallocarray(prog->insns, new_cnt, sizeof(*insn));
1119 if (!new_insn) {1121 if (!new_insn) {
1120 pr_warning("oom in prog realloc\n");1122 pr_warning("oom in prog realloc\n");
1121 return -ENOMEM;1123 return -ENOMEM;

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