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Subject[PATCH v4 1/3] bpf: bpf_prog_array_copy() should return -ENOENT if exclude_prog not found
Date
This makes is it possible for bpf prog detach to return -ENOENT.

Signed-off-by: Sean Young <sean@mess.org>
---
kernel/bpf/core.c | 11 +++++++++--
kernel/trace/bpf_trace.c | 2 ++
2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 2194c6a9df42..198848837783 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1566,6 +1566,7 @@ 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
@@ -1574,14 +1575,20 @@ 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 ce2cbbff27e4..daf36acb2a17 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1005,6 +1005,8 @@ 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 {
--
2.17.0
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