libbpf: Remove any use of reallocarray() in libbpf

Re-implement glibc's reallocarray() for libbpf internal-only use.
reallocarray(), unfortunately, is not available in all versions of glibc, so
requires extra feature detection and using reallocarray() stub from
<tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates build
of libbpf unnecessarily and is just a maintenance burden. Instead, it's
trivial to implement libbpf-specific internal version and use it throughout
libbpf.

Which is what this patch does, along with converting some realloc() uses that
should really have been reallocarray() in the first place.

Signed-off-by: Andrii Nakryiko <andriin@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20200819013607.3607269-2-andriin@fb.com

diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
index 95c946e94ca5f27a517f4e0a62538bc075bc4f6d..621ad96d06fdabc9fdb31f3d72d688e76f35f131 100644 (file)
--- a/tools/lib/bpf/Makefile
+++ b/tools/lib/bpf/Makefile
@@ -56,7 +56,7 @@ ifndef VERBOSE
 endif
 
 FEATURE_USER = .libbpf
-FEATURE_TESTS = libelf libelf-mmap zlib bpf reallocarray
+FEATURE_TESTS = libelf libelf-mmap zlib bpf
 FEATURE_DISPLAY = libelf zlib bpf
 
 INCLUDES = -I. -I$(srctree)/tools/include -I$(srctree)/tools/arch/$(ARCH)/include/uapi -I$(srctree)/tools/include/uapi
@@ -102,10 +102,6 @@ ifeq ($(feature-libelf-mmap), 1)
   override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
 endif
 
-ifeq ($(feature-reallocarray), 0)
-  override CFLAGS += -DCOMPAT_NEED_REALLOCARRAY
-endif
-
 # Append required CFLAGS
 override CFLAGS += $(EXTRA_WARNINGS) -Wno-switch-enum
 override CFLAGS += -Werror -Wall

diff --git a/tools/lib/bpf/btf.c b/tools/lib/bpf/btf.c
index 1deedbd19c6c7629f4afc42664e6458e35dd0f79..1b7d85d94a07eb79a1a73edf51c5ac4ba51c1c9c 100644 (file)
--- a/tools/lib/bpf/btf.c
+++ b/tools/lib/bpf/btf.c
@@ -61,7 +61,7 @@ static int btf_add_type(struct btf *btf, struct btf_type *t)
                expand_by = max(btf->types_size >> 2, 16U);
                new_size = min(BTF_MAX_NR_TYPES, btf->types_size + expand_by);
 
-               new_types = realloc(btf->types, sizeof(*new_types) * new_size);
+               new_types = libbpf_reallocarray(btf->types, new_size, sizeof(*new_types));
                if (!new_types)
                        return -ENOMEM;
 
@@ -1574,7 +1574,7 @@ static int btf_dedup_hypot_map_add(struct btf_dedup *d,
                __u32 *new_list;
 
                d->hypot_cap += max((size_t)16, d->hypot_cap / 2);
-               new_list = realloc(d->hypot_list, sizeof(__u32) * d->hypot_cap);
+               new_list = libbpf_reallocarray(d->hypot_list, d->hypot_cap, sizeof(__u32));
                if (!new_list)
                        return -ENOMEM;
                d->hypot_list = new_list;
@@ -1870,8 +1870,7 @@ static int btf_dedup_strings(struct btf_dedup *d)
                        struct btf_str_ptr *new_ptrs;
 
                        strs.cap += max(strs.cnt / 2, 16U);
-                       new_ptrs = realloc(strs.ptrs,
-                                          sizeof(strs.ptrs[0]) * strs.cap);
+                       new_ptrs = libbpf_reallocarray(strs.ptrs, strs.cap, sizeof(strs.ptrs[0]));
                        if (!new_ptrs) {
                                err = -ENOMEM;
                                goto done;
@@ -2956,8 +2955,8 @@ static int btf_dedup_compact_types(struct btf_dedup *d)
        d->btf->nr_types = next_type_id - 1;
        d->btf->types_size = d->btf->nr_types;
        d->btf->hdr->type_len = p - types_start;
-       new_types = realloc(d->btf->types,
-                           (1 + d->btf->nr_types) * sizeof(struct btf_type *));
+       new_types = libbpf_reallocarray(d->btf->types, (1 + d->btf->nr_types),
+                                       sizeof(struct btf_type *));
        if (!new_types)
                return -ENOMEM;
        d->btf->types = new_types;

diff --git a/tools/lib/bpf/btf_dump.c b/tools/lib/bpf/btf_dump.c
index fe39bd7746976890707a252f49466026cc6861db..1ad852ad0a86bcd24c9152e71af18d545028a41d 100644 (file)
--- a/tools/lib/bpf/btf_dump.c
+++ b/tools/lib/bpf/btf_dump.c
@@ -323,8 +323,7 @@ static int btf_dump_add_emit_queue_id(struct btf_dump *d, __u32 id)
 
        if (d->emit_queue_cnt >= d->emit_queue_cap) {
                new_cap = max(16, d->emit_queue_cap * 3 / 2);
-               new_queue = realloc(d->emit_queue,
-                                   new_cap * sizeof(new_queue[0]));
+               new_queue = libbpf_reallocarray(d->emit_queue, new_cap, sizeof(new_queue[0]));
                if (!new_queue)
                        return -ENOMEM;
                d->emit_queue = new_queue;
@@ -1003,8 +1002,7 @@ static int btf_dump_push_decl_stack_id(struct btf_dump *d, __u32 id)
 
        if (d->decl_stack_cnt >= d->decl_stack_cap) {
                new_cap = max(16, d->decl_stack_cap * 3 / 2);
-               new_stack = realloc(d->decl_stack,
-                                   new_cap * sizeof(new_stack[0]));
+               new_stack = libbpf_reallocarray(d->decl_stack, new_cap, sizeof(new_stack[0]));
                if (!new_stack)
                        return -ENOMEM;
                d->decl_stack = new_stack;

diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
index 0276cf85d763169b41777beeb4f8ceb259ec0d7c..2653bcee73b778985e031f1eeed488684b87b1d3 100644 (file)
--- a/tools/lib/bpf/libbpf.c
+++ b/tools/lib/bpf/libbpf.c
@@ -44,7 +44,6 @@
 #include <sys/vfs.h>
 #include <sys/utsname.h>
 #include <sys/resource.h>
-#include <tools/libc_compat.h>
 #include <libelf.h>
 #include <gelf.h>
 #include <zlib.h>
@@ -567,7 +566,7 @@ bpf_object__add_program(struct bpf_object *obj, void *data, size_t size,
        progs = obj->programs;
        nr_progs = obj->nr_programs;
 
-       progs = reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
+       progs = libbpf_reallocarray(progs, nr_progs + 1, sizeof(progs[0]));
        if (!progs) {
                /*
                 * In this case the original obj->programs
@@ -1292,7 +1291,7 @@ static struct bpf_map *bpf_object__add_map(struct bpf_object *obj)
                return &obj->maps[obj->nr_maps++];
 
        new_cap = max((size_t)4, obj->maps_cap * 3 / 2);
-       new_maps = realloc(obj->maps, new_cap * sizeof(*obj->maps));
+       new_maps = libbpf_reallocarray(obj->maps, new_cap, sizeof(*obj->maps));
        if (!new_maps) {
                pr_warn("alloc maps for object failed\n");
                return ERR_PTR(-ENOMEM);
@@ -2721,8 +2720,8 @@ static int bpf_object__elf_collect(struct bpf_object *obj)
                                continue;
                        }
 
-                       sects = reallocarray(sects, nr_sects + 1,
-                                            sizeof(*obj->efile.reloc_sects));
+                       sects = libbpf_reallocarray(sects, nr_sects + 1,
+                                                   sizeof(*obj->efile.reloc_sects));
                        if (!sects) {
                                pr_warn("reloc_sects realloc failed\n");
                                return -ENOMEM;
@@ -2925,7 +2924,7 @@ static int bpf_object__collect_externs(struct bpf_object *obj)
                        continue;
 
                ext = obj->externs;
-               ext = reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
+               ext = libbpf_reallocarray(ext, obj->nr_extern + 1, sizeof(*ext));
                if (!ext)
                        return -ENOMEM;
                obj->externs = ext;
@@ -4362,9 +4361,9 @@ static struct ids_vec *bpf_core_find_cands(const struct btf *local_btf,
                        pr_debug("CO-RE relocating [%d] %s %s: found target candidate [%d] %s %s\n",
                                 local_type_id, btf_kind_str(local_t),
                                 local_name, i, targ_kind, targ_name);
-                       new_ids = reallocarray(cand_ids->data,
-                                              cand_ids->len + 1,
-                                              sizeof(*cand_ids->data));
+                       new_ids = libbpf_reallocarray(cand_ids->data,
+                                                     cand_ids->len + 1,
+                                                     sizeof(*cand_ids->data));
                        if (!new_ids) {
                                err = -ENOMEM;
                                goto err_out;
@@ -5231,7 +5230,7 @@ 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 = reallocarray(prog->insns, new_cnt, sizeof(*insn));
+               new_insn = libbpf_reallocarray(prog->insns, new_cnt, sizeof(*insn));
                if (!new_insn) {
                        pr_warn("oom in prog realloc\n");
                        return -ENOMEM;
@@ -5473,7 +5472,7 @@ static int bpf_object__collect_map_relos(struct bpf_object *obj,
                moff /= bpf_ptr_sz;
                if (moff >= map->init_slots_sz) {
                        new_sz = moff + 1;
-                       tmp = realloc(map->init_slots, new_sz * host_ptr_sz);
+                       tmp = libbpf_reallocarray(map->init_slots, new_sz, host_ptr_sz);
                        if (!tmp)
                                return -ENOMEM;
                        map->init_slots = tmp;

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index b776a7125c9286286cbc39cb2f712bdabeb73b90..954bc2bd040c843e556047c76872e58ea0282d7d 100644 (file)
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -9,6 +9,7 @@
 #ifndef __LIBBPF_LIBBPF_INTERNAL_H
 #define __LIBBPF_LIBBPF_INTERNAL_H
 
+#include <stdlib.h>
 #include "libbpf.h"
 
 #define BTF_INFO_ENC(kind, kind_flag, vlen) \
@@ -23,6 +24,12 @@
 #define BTF_PARAM_ENC(name, type) (name), (type)
 #define BTF_VAR_SECINFO_ENC(type, offset, size) (type), (offset), (size)
 
+#ifndef likely
+#define likely(x) __builtin_expect(!!(x), 1)
+#endif
+#ifndef unlikely
+#define unlikely(x) __builtin_expect(!!(x), 0)
+#endif
 #ifndef min
 # define min(x, y) ((x) < (y) ? (x) : (y))
 #endif
@@ -63,6 +70,24 @@ do {                         \
 #define pr_info(fmt, ...)      __pr(LIBBPF_INFO, fmt, ##__VA_ARGS__)
 #define pr_debug(fmt, ...)     __pr(LIBBPF_DEBUG, fmt, ##__VA_ARGS__)
 
+/*
+ * Re-implement glibc's reallocarray() for libbpf internal-only use.
+ * reallocarray(), unfortunately, is not available in all versions of glibc,
+ * so requires extra feature detection and using reallocarray() stub from
+ * <tools/libc_compat.h> and COMPAT_NEED_REALLOCARRAY. All this complicates
+ * build of libbpf unnecessarily and is just a maintenance burden. Instead,
+ * it's trivial to implement libbpf-specific internal version and use it
+ * throughout libbpf.
+ */
+static inline void *libbpf_reallocarray(void *ptr, size_t nmemb, size_t size)
+{
+       size_t total;
+
+       if (unlikely(__builtin_mul_overflow(nmemb, size, &total)))
+               return NULL;
+       return realloc(ptr, total);
+}
+
 static inline bool libbpf_validate_opts(const char *opts,
                                        size_t opts_sz, size_t user_sz,
                                        const char *type_name)

diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c
index 4fc6c6cbb4eb9829c2ce7de250723749142cf269..5bd234be8a147a61054d8d453916b9b9f2c19215 100644 (file)
--- a/tools/lib/bpf/ringbuf.c
+++ b/tools/lib/bpf/ringbuf.c
@@ -16,7 +16,6 @@
 #include <asm/barrier.h>
 #include <sys/mman.h>
 #include <sys/epoll.h>
-#include <tools/libc_compat.h>
 
 #include "libbpf.h"
 #include "libbpf_internal.h"
@@ -82,12 +81,12 @@ int ring_buffer__add(struct ring_buffer *rb, int map_fd,
                return -EINVAL;
        }
 
-       tmp = reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
+       tmp = libbpf_reallocarray(rb->rings, rb->ring_cnt + 1, sizeof(*rb->rings));
        if (!tmp)
                return -ENOMEM;
        rb->rings = tmp;
 
-       tmp = reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
+       tmp = libbpf_reallocarray(rb->events, rb->ring_cnt + 1, sizeof(*rb->events));
        if (!tmp)
                return -ENOMEM;
        rb->events = tmp;