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 <yhs@fb.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

2 files changed, 11 insertions, 2 deletions

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index b574dddc05b8..527587de8a67 100644
--- 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
index 81fdf2fc94ac..af1486d9a0ed 100644
--- 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 {