From: Hengqi Chen <chenhengqi@outlook.com>
Date: Sat, 23 Oct 2021 15:04:27 +0000 (+0800)
Subject: libbpf-tools: Fix memory leaks in ksnoop/gethostlatency
X-Git-Tag: v0.23.0~7^2
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=e9f140f0fea0ba2fcd9af9ec4ede1e957a25a1b1;p=platform%2Fupstream%2Fbcc.git

libbpf-tools: Fix memory leaks in ksnoop/gethostlatency

There are memory leaks when attach a BPF program to multiple
targets in these tools. This is because we misuse the
bpf_program__attach_kprobe function, the returned struct bpf_link
object is not freed after use. Closes #3664.

Signed-off-by: Hengqi Chen <chenhengqi@outlook.com>
---

diff --git a/libbpf-tools/gethostlatency.c b/libbpf-tools/gethostlatency.c
index 34859818..d1019d18 100644
--- a/libbpf-tools/gethostlatency.c
+++ b/libbpf-tools/gethostlatency.c
@@ -133,7 +133,7 @@ static int get_libc_path(char *path)
 	return -1;
 }
 
-static int attach_uprobes(struct gethostlatency_bpf *obj)
+static int attach_uprobes(struct gethostlatency_bpf *obj, struct bpf_link *links[])
 {
 	int err;
 	char libc_path[PATH_MAX] = {};
@@ -150,18 +150,16 @@ static int attach_uprobes(struct gethostlatency_bpf *obj)
 		warn("could not find getaddrinfo in %s\n", libc_path);
 		return -1;
 	}
-	obj->links.handle_entry =
-		bpf_program__attach_uprobe(obj->progs.handle_entry, false,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_entry);
+	links[0] = bpf_program__attach_uprobe(obj->progs.handle_entry, false,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[0]);
 	if (err) {
 		warn("failed to attach getaddrinfo: %d\n", err);
 		return -1;
 	}
-	obj->links.handle_return =
-		bpf_program__attach_uprobe(obj->progs.handle_return, true,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_return);
+	links[1] = bpf_program__attach_uprobe(obj->progs.handle_return, true,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[1]);
 	if (err) {
 		warn("failed to attach getaddrinfo: %d\n", err);
 		return -1;
@@ -172,18 +170,16 @@ static int attach_uprobes(struct gethostlatency_bpf *obj)
 		warn("could not find gethostbyname in %s\n", libc_path);
 		return -1;
 	}
-	obj->links.handle_entry =
-		bpf_program__attach_uprobe(obj->progs.handle_entry, false,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_entry);
+	links[2] = bpf_program__attach_uprobe(obj->progs.handle_entry, false,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[2]);
 	if (err) {
 		warn("failed to attach gethostbyname: %d\n", err);
 		return -1;
 	}
-	obj->links.handle_return =
-		bpf_program__attach_uprobe(obj->progs.handle_return, true,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_return);
+	links[3] = bpf_program__attach_uprobe(obj->progs.handle_return, true,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[3]);
 	if (err) {
 		warn("failed to attach gethostbyname: %d\n", err);
 		return -1;
@@ -194,18 +190,16 @@ static int attach_uprobes(struct gethostlatency_bpf *obj)
 		warn("could not find gethostbyname2 in %s\n", libc_path);
 		return -1;
 	}
-	obj->links.handle_entry =
-		bpf_program__attach_uprobe(obj->progs.handle_entry, false,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_entry);
+	links[4] = bpf_program__attach_uprobe(obj->progs.handle_entry, false,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[4]);
 	if (err) {
 		warn("failed to attach gethostbyname2: %d\n", err);
 		return -1;
 	}
-	obj->links.handle_return =
-		bpf_program__attach_uprobe(obj->progs.handle_return, true,
-					   target_pid ?: -1, libc_path, func_off);
-	err = libbpf_get_error(obj->links.handle_return);
+	links[5] = bpf_program__attach_uprobe(obj->progs.handle_return, true,
+					      target_pid ?: -1, libc_path, func_off);
+	err = libbpf_get_error(links[5]);
 	if (err) {
 		warn("failed to attach gethostbyname2: %d\n", err);
 		return -1;
@@ -223,8 +217,9 @@ int main(int argc, char **argv)
 	};
 	struct perf_buffer_opts pb_opts;
 	struct perf_buffer *pb = NULL;
+	struct bpf_link *links[6] = {};
 	struct gethostlatency_bpf *obj;
-	int err;
+	int i, err;
 
 	err = argp_parse(&argp, argc, argv, 0, NULL, NULL);
 	if (err)
@@ -250,7 +245,7 @@ int main(int argc, char **argv)
 		goto cleanup;
 	}
 
-	err = attach_uprobes(obj);
+	err = attach_uprobes(obj, links);
 	if (err)
 		goto cleanup;
 
@@ -285,6 +280,8 @@ int main(int argc, char **argv)
 
 cleanup:
 	perf_buffer__free(pb);
+	for (i = 0; i < 6; i++)
+		bpf_link__destroy(links[i]);
 	gethostlatency_bpf__destroy(obj);
 
 	return err != 0;
diff --git a/libbpf-tools/ksnoop.c b/libbpf-tools/ksnoop.c
index 896b25a6..ce8b240b 100644
--- a/libbpf-tools/ksnoop.c
+++ b/libbpf-tools/ksnoop.c
@@ -669,7 +669,7 @@ static int parse_traces(int argc, char **argv, struct trace **traces)
 
 static int cmd_info(int argc, char **argv)
 {
-	struct trace *traces;
+	struct trace *traces = NULL;
 	char str[MAX_STR];
 	int nr_traces;
 	__u8 i, j;
@@ -696,6 +696,7 @@ static int cmd_info(int argc, char **argv)
 			       func->nr_args - MAX_ARGS);
 		printf(");\n");
 	}
+	free(traces);
 	return 0;
 }
 
@@ -815,14 +816,14 @@ static int add_traces(struct bpf_map *func_map, struct trace *traces,
 static int attach_traces(struct ksnoop_bpf *skel, struct trace *traces,
 			 int nr_traces)
 {
-	struct bpf_link *link;
 	int i, ret;
 
 	for (i = 0; i < nr_traces; i++) {
-		link = bpf_program__attach_kprobe(skel->progs.kprobe_entry,
-						  false,
-						  traces[i].func.name);
-		ret = libbpf_get_error(link);
+		traces[i].links[0] =
+			bpf_program__attach_kprobe(skel->progs.kprobe_entry,
+						   false,
+						   traces[i].func.name);
+		ret = libbpf_get_error(traces[i].links[0]);
 		if (ret) {
 			p_err("Could not attach kprobe to '%s': %s",
 			      traces[i].func.name, strerror(-ret));
@@ -830,10 +831,11 @@ static int attach_traces(struct ksnoop_bpf *skel, struct trace *traces,
 			}
 		p_debug("Attached kprobe for '%s'", traces[i].func.name);
 
-		link = bpf_program__attach_kprobe(skel->progs.kprobe_return,
-						  true,
-						  traces[i].func.name);
-		ret = libbpf_get_error(link);
+		traces[i].links[1] =
+			bpf_program__attach_kprobe(skel->progs.kprobe_return,
+						   true,
+						   traces[i].func.name);
+		ret = libbpf_get_error(traces[i].links[1]);
 		if (ret) {
 			p_err("Could not attach kretprobe to '%s': %s",
 			      traces[i].func.name, strerror(-ret));
@@ -848,10 +850,10 @@ static int cmd_trace(int argc, char **argv)
 {
 	struct perf_buffer_opts pb_opts = {};
 	struct bpf_map *perf_map, *func_map;
-	struct perf_buffer *pb;
+	struct perf_buffer *pb = NULL;
 	struct ksnoop_bpf *skel;
-	int nr_traces, ret = 0;
-	struct trace *traces;
+	int i, nr_traces, ret = -1;
+	struct trace *traces = NULL;
 
 	nr_traces = parse_traces(argc, argv, &traces);
 	if (nr_traces < 0)
@@ -866,22 +868,22 @@ static int cmd_trace(int argc, char **argv)
 	perf_map = skel->maps.ksnoop_perf_map;
 	if (!perf_map) {
 		p_err("Could not find '%s'", "ksnoop_perf_map");
-		return 1;
+		goto cleanup;
 	}
 	func_map = bpf_object__find_map_by_name(skel->obj, "ksnoop_func_map");
 	if (!func_map) {
 		p_err("Could not find '%s'", "ksnoop_func_map");
-		return 1;
+		goto cleanup;
 	}
 
 	if (add_traces(func_map, traces, nr_traces)) {
 		p_err("Could not add traces to '%s'", "ksnoop_func_map");
-		return 1;
+		goto cleanup;
 	}
 
 	if (attach_traces(skel, traces, nr_traces)) {
 		p_err("Could not attach %d traces", nr_traces);
-		return 1;
+		goto cleanup;
 	}
 
 	pb_opts.sample_cb = trace_handler;
@@ -890,7 +892,7 @@ static int cmd_trace(int argc, char **argv)
 	if (libbpf_get_error(pb)) {
 		p_err("Could not create perf buffer: %s",
 		      libbpf_errstr(pb));
-		return 1;
+		goto cleanup;
 	}
 
 	printf("%16s %4s %8s %s\n", "TIME", "CPU", "PID", "FUNCTION/ARGS");
@@ -912,6 +914,11 @@ static int cmd_trace(int argc, char **argv)
 	}
 
 cleanup:
+	for (i = 0; i < nr_traces; i++) {
+		bpf_link__destroy(traces[i].links[0]);
+		bpf_link__destroy(traces[i].links[1]);
+	}
+	free(traces);
 	perf_buffer__free(pb);
 	ksnoop_bpf__destroy(skel);
 
diff --git a/libbpf-tools/ksnoop.h b/libbpf-tools/ksnoop.h
index 6c55b0ef..6b33df4e 100644
--- a/libbpf-tools/ksnoop.h
+++ b/libbpf-tools/ksnoop.h
@@ -24,8 +24,8 @@ enum arg {
  */
 #define KSNOOP_ID_UNKNOWN		0xffffffff
 
-#define MAX_NAME			96	
-#define MAX_STR				256	
+#define MAX_NAME			96
+#define MAX_STR				256
 #define MAX_PATH			512
 #define MAX_VALUES			6
 #define MAX_ARGS			(MAX_VALUES - 1)
@@ -112,6 +112,7 @@ struct trace {
 	__u16 buf_len;
 	char buf[MAX_TRACE_BUF];
 	char buf_end[0];
+	struct bpf_link *links[2];
 };
 
 #define PAGES_DEFAULT	16