bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not …

…found This makes is it possible for bpf prog detach to return -ENOENT. Acked-by: Yonghong Song <[email protected]> Signed-off-by: Sean Young <[email protected]> Signed-off-by: Daniel Borkmann <[email protected]>
ambv · May 30, 2018 · 170a7e3 · 170a7e3
1 parent 9ce64f1
commit 170a7e3
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
@@ -1616,6 +1616,7 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
 	int new_prog_cnt, carry_prog_cnt = 0;
 	struct bpf_prog **existing_prog;
 	struct bpf_prog_array *array;
+	bool found_exclude = false;
 	int new_prog_idx = 0;
 
 	/* Figure out how many existing progs we need to carry over to
@@ -1624,14 +1625,20 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
 	if (old_array) {
 		existing_prog = old_array->progs;
 		for (; *existing_prog; existing_prog++) {
-			if (*existing_prog != exclude_prog &&
-			    *existing_prog != &dummy_bpf_prog.prog)
+			if (*existing_prog == exclude_prog) {
+				found_exclude = true;
+				continue;
+			}
+			if (*existing_prog != &dummy_bpf_prog.prog)
 				carry_prog_cnt++;
 			if (*existing_prog == include_prog)
 				return -EEXIST;
 		}
 	}
 
+	if (exclude_prog && !found_exclude)
+		return -ENOENT;
+
 	/* How many progs (not NULL) will be in the new array? */
 	new_prog_cnt = carry_prog_cnt;
 	if (include_prog)

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
@@ -1006,6 +1006,8 @@ void perf_event_detach_bpf_prog(struct perf_event *event)
 
 	old_array = event->tp_event->prog_array;
 	ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);
+	if (ret == -ENOENT)
+		goto unlock;
 	if (ret < 0) {
 		bpf_prog_array_delete_safe(old_array, event->prog);
 	} else {