bpf-fixes

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Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf

Pull bpf fixes from Alexei Starovoitov:

 - Fix handling of BPF arena relocations (Andrii Nakryiko)

 - Fix race in bpf_arch_text_poke() on s390 (Ilya Leoshkevich)

 - Fix use of virt_to_phys() on arm64 when mmapping BTF (Lorenz Bauer)

 - Reject %p% format string in bprintf-like BPF helpers (Paul Chaignon)

* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
  libbpf: Fix handling of BPF arena relocations
  btf: Fix virt_to_phys() on arm64 when mmapping BTF
  selftests/bpf: Stress test attaching a BPF prog to another BPF prog
  s390/bpf: Fix bpf_arch_text_poke() with new_addr == NULL again
  selftests/bpf: Add negative test cases for snprintf
  bpf: Reject %p% format string in bprintf-like helpers

arch/s390/net/bpf_jit_comp.c

@@ -566,7 +566,15 @@ static void bpf_jit_plt(struct bpf_plt *plt, void *ret, void *target)
 {
 	memcpy(plt, &bpf_plt, sizeof(*plt));
 	plt->ret = ret;
-	plt->target = target;
+	/*
+	 * (target == NULL) implies that the branch to this PLT entry was
+	 * patched and became a no-op. However, some CPU could have jumped
+	 * to this PLT entry before patching and may be still executing it.
+	 *
+	 * Since the intention in this case is to make the PLT entry a no-op,
+	 * make the target point to the return label instead of NULL.
+	 */
+	plt->target = target ?: ret;
 }
 
 /*

kernel/bpf/helpers.c

@@ -884,6 +884,13 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
 		if (fmt[i] == 'p') {
 			sizeof_cur_arg = sizeof(long);
 
+			if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) ||
+			    ispunct(fmt[i + 1])) {
+				if (tmp_buf)
+					cur_arg = raw_args[num_spec];
+				goto nocopy_fmt;
+			}
+
 			if ((fmt[i + 1] == 'k' || fmt[i + 1] == 'u') &&
 			    fmt[i + 2] == 's') {
 				fmt_ptype = fmt[i + 1];
@@ -891,11 +898,9 @@ int bpf_bprintf_prepare(char *fmt, u32 fmt_size, const u64 *raw_args,
 				goto fmt_str;
 			}
 
-			if (fmt[i + 1] == 0 || isspace(fmt[i + 1]) ||
+			if (fmt[i + 1] == 'K' ||
-			    ispunct(fmt[i + 1]) || fmt[i + 1] == 'K' ||
 			    fmt[i + 1] == 'x' || fmt[i + 1] == 's' ||
 			    fmt[i + 1] == 'S') {
-				/* just kernel pointers */
 				if (tmp_buf)
 					cur_arg = raw_args[num_spec];
 				i++;

kernel/bpf/sysfs_btf.c

@@ -21,7 +21,7 @@ static int btf_sysfs_vmlinux_mmap(struct file *filp, struct kobject *kobj,
 {
 	unsigned long pages = PAGE_ALIGN(attr->size) >> PAGE_SHIFT;
 	size_t vm_size = vma->vm_end - vma->vm_start;
-	phys_addr_t addr = virt_to_phys(__start_BTF);
+	phys_addr_t addr = __pa_symbol(__start_BTF);
 	unsigned long pfn = addr >> PAGE_SHIFT;
 
 	if (attr->private != __start_BTF || !PAGE_ALIGNED(addr))

tools/lib/bpf/libbpf.c

@@ -735,7 +735,7 @@ struct bpf_object {
 
 	struct usdt_manager *usdt_man;
 
-	struct bpf_map *arena_map;
+	int arena_map_idx;
 	void *arena_data;
 	size_t arena_data_sz;
 
@@ -1517,6 +1517,7 @@ static struct bpf_object *bpf_object__new(const char *path,
 	obj->efile.obj_buf_sz = obj_buf_sz;
 	obj->efile.btf_maps_shndx = -1;
 	obj->kconfig_map_idx = -1;
+	obj->arena_map_idx = -1;
 
 	obj->kern_version = get_kernel_version();
 	obj->state  = OBJ_OPEN;
@@ -2964,7 +2965,7 @@ static int init_arena_map_data(struct bpf_object *obj, struct bpf_map *map,
 	const long page_sz = sysconf(_SC_PAGE_SIZE);
 	size_t mmap_sz;
 
-	mmap_sz = bpf_map_mmap_sz(obj->arena_map);
+	mmap_sz = bpf_map_mmap_sz(map);
 	if (roundup(data_sz, page_sz) > mmap_sz) {
 		pr_warn("elf: sec '%s': declared ARENA map size (%zu) is too small to hold global __arena variables of size %zu\n",
 			sec_name, mmap_sz, data_sz);
@@ -3038,12 +3039,12 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
 		if (map->def.type != BPF_MAP_TYPE_ARENA)
 			continue;
 
-		if (obj->arena_map) {
+		if (obj->arena_map_idx >= 0) {
 			pr_warn("map '%s': only single ARENA map is supported (map '%s' is also ARENA)\n",
-				map->name, obj->arena_map->name);
+				map->name, obj->maps[obj->arena_map_idx].name);
 			return -EINVAL;
 		}
-		obj->arena_map = map;
+		obj->arena_map_idx = i;
 
 		if (obj->efile.arena_data) {
 			err = init_arena_map_data(obj, map, ARENA_SEC, obj->efile.arena_data_shndx,
@@ -3053,7 +3054,7 @@ static int bpf_object__init_user_btf_maps(struct bpf_object *obj, bool strict,
 				return err;
 		}
 	}
-	if (obj->efile.arena_data && !obj->arena_map) {
+	if (obj->efile.arena_data && obj->arena_map_idx < 0) {
 		pr_warn("elf: sec '%s': to use global __arena variables the ARENA map should be explicitly declared in SEC(\".maps\")\n",
 			ARENA_SEC);
 		return -ENOENT;
@@ -4583,8 +4584,13 @@ static int bpf_program__record_reloc(struct bpf_program *prog,
 	if (shdr_idx == obj->efile.arena_data_shndx) {
 		reloc_desc->type = RELO_DATA;
 		reloc_desc->insn_idx = insn_idx;
-		reloc_desc->map_idx = obj->arena_map - obj->maps;
+		reloc_desc->map_idx = obj->arena_map_idx;
 		reloc_desc->sym_off = sym->st_value;
+
+		map = &obj->maps[obj->arena_map_idx];
+		pr_debug("prog '%s': found arena map %d (%s, sec %d, off %zu) for insn %u\n",
+			 prog->name, obj->arena_map_idx, map->name, map->sec_idx,
+			 map->sec_offset, insn_idx);
 		return 0;
 	}
 

tools/testing/selftests/bpf/prog_tests/recursive_attach.c

@@ -149,3 +149,70 @@ close_prog:
 	fentry_recursive_target__destroy(target_skel);
 	fentry_recursive__destroy(tracing_skel);
 }
+
+static void *fentry_target_test_run(void *arg)
+{
+	for (;;) {
+		int prog_fd = __atomic_load_n((int *)arg, __ATOMIC_SEQ_CST);
+		LIBBPF_OPTS(bpf_test_run_opts, topts);
+		int err;
+
+		if (prog_fd == -1)
+			break;
+		err = bpf_prog_test_run_opts(prog_fd, &topts);
+		if (!ASSERT_OK(err, "fentry_target test_run"))
+			break;
+	}
+
+	return NULL;
+}
+
+void test_fentry_attach_stress(void)
+{
+	struct fentry_recursive_target *target_skel = NULL;
+	struct fentry_recursive *tracing_skel = NULL;
+	struct bpf_program *prog;
+	int err, i, tgt_prog_fd;
+	pthread_t thread;
+
+	target_skel = fentry_recursive_target__open_and_load();
+	if (!ASSERT_OK_PTR(target_skel,
+			   "fentry_recursive_target__open_and_load"))
+		goto close_prog;
+	tgt_prog_fd = bpf_program__fd(target_skel->progs.fentry_target);
+	err = pthread_create(&thread, NULL,
+			     fentry_target_test_run, &tgt_prog_fd);
+	if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
+		goto close_prog;
+
+	for (i = 0; i < 1000; i++) {
+		tracing_skel = fentry_recursive__open();
+		if (!ASSERT_OK_PTR(tracing_skel, "fentry_recursive__open"))
+			goto stop_thread;
+
+		prog = tracing_skel->progs.recursive_attach;
+		err = bpf_program__set_attach_target(prog, tgt_prog_fd,
+						     "fentry_target");
+		if (!ASSERT_OK(err, "bpf_program__set_attach_target"))
+			goto stop_thread;
+
+		err = fentry_recursive__load(tracing_skel);
+		if (!ASSERT_OK(err, "fentry_recursive__load"))
+			goto stop_thread;
+
+		err = fentry_recursive__attach(tracing_skel);
+		if (!ASSERT_OK(err, "fentry_recursive__attach"))
+			goto stop_thread;
+
+		fentry_recursive__destroy(tracing_skel);
+		tracing_skel = NULL;
+	}
+
+stop_thread:
+	__atomic_store_n(&tgt_prog_fd, -1, __ATOMIC_SEQ_CST);
+	err = pthread_join(thread, NULL);
+	ASSERT_OK(err, "pthread_join");
+close_prog:
+	fentry_recursive__destroy(tracing_skel);
+	fentry_recursive_target__destroy(target_skel);
+}

tools/testing/selftests/bpf/prog_tests/snprintf.c

@@ -116,6 +116,8 @@ static void test_snprintf_negative(void)
 	ASSERT_ERR(load_single_snprintf("%llc"), "invalid specifier 7");
 	ASSERT_ERR(load_single_snprintf("\x80"), "non ascii character");
 	ASSERT_ERR(load_single_snprintf("\x1"), "non printable character");
+	ASSERT_ERR(load_single_snprintf("%p%"), "invalid specifier 8");
+	ASSERT_ERR(load_single_snprintf("%s%"), "invalid specifier 9");
 }
 
 void test_snprintf(void)