From: Sean Young <sean@mess.org>
Date: Sun, 27 May 2018 12:24:08 +0100
Subject: bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not
 found
Patch-mainline: v4.18-rc1
Git-commit: 170a7e3ea0709eae12c8f944b9f33c54fe80c6c1
References: bsc#1109837

This makes is it possible for bpf prog detach to return -ENOENT.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/core.c        |   11 +++++++++--
 kernel/trace/bpf_trace.c |    2 ++
 2 files changed, 11 insertions(+), 2 deletions(-)

--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1619,6 +1619,7 @@ int bpf_prog_array_copy(struct bpf_prog_
 	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
@@ -1627,14 +1628,20 @@ int bpf_prog_array_copy(struct bpf_prog_
 	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)
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -971,6 +971,8 @@ void perf_event_detach_bpf_prog(struct p
 
 	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 {