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Commit e672db03 authored by Stanislav Fomichev's avatar Stanislav Fomichev Committed by Daniel Borkmann
Browse files

bpf: tracing: properly use bpf_prog_array api 



Now that we don't have __rcu markers on the bpf_prog_array helpers,
let's use proper rcu_dereference_protected to obtain array pointer
under mutex.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: default avatarStanislav Fomichev <sdf@google.com>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
parent dbcc1ba2

kernel/trace/bpf_trace.c

+10 −8
Original line number Diff line number Diff line
@@ -19,6 +19,9 @@ 
#include "trace_probe.h"

#include "trace.h"



#define bpf_event_rcu_dereference(p)					\

	rcu_dereference_protected(p, lockdep_is_held(&bpf_event_mutex))



#ifdef CONFIG_MODULES

struct bpf_trace_module {

	struct module *module;
@@ -1099,7 +1102,7 @@ static DEFINE_MUTEX(bpf_event_mutex); 
int perf_event_attach_bpf_prog(struct perf_event *event,

			       struct bpf_prog *prog)

{

	struct bpf_prog_array __rcu *old_array;

	struct bpf_prog_array *old_array;

	struct bpf_prog_array *new_array;

	int ret = -EEXIST;
@@ -1117,7 +1120,7 @@ int perf_event_attach_bpf_prog(struct perf_event *event, 
	if (event->prog)

		goto unlock;



	old_array = event->tp_event->prog_array;

	old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);

	if (old_array &&

	    bpf_prog_array_length(old_array) >= BPF_TRACE_MAX_PROGS) {

		ret = -E2BIG;
@@ -1140,7 +1143,7 @@ int perf_event_attach_bpf_prog(struct perf_event *event, 


void perf_event_detach_bpf_prog(struct perf_event *event)

{

	struct bpf_prog_array __rcu *old_array;

	struct bpf_prog_array *old_array;

	struct bpf_prog_array *new_array;

	int ret;
@@ -1149,7 +1152,7 @@ void perf_event_detach_bpf_prog(struct perf_event *event) 
	if (!event->prog)

		goto unlock;



	old_array = event->tp_event->prog_array;

	old_array = bpf_event_rcu_dereference(event->tp_event->prog_array);

	ret = bpf_prog_array_copy(old_array, event->prog, NULL, &new_array);

	if (ret == -ENOENT)

		goto unlock;
@@ -1171,6 +1174,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) 
{

	struct perf_event_query_bpf __user *uquery = info;

	struct perf_event_query_bpf query = {};

	struct bpf_prog_array *progs;

	u32 *ids, prog_cnt, ids_len;

	int ret;
@@ -1195,10 +1199,8 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info) 
	 */



	mutex_lock(&bpf_event_mutex);

	ret = bpf_prog_array_copy_info(event->tp_event->prog_array,

				       ids,

				       ids_len,

				       &prog_cnt);

	progs = bpf_event_rcu_dereference(event->tp_event->prog_array);

	ret = bpf_prog_array_copy_info(progs, ids, ids_len, &prog_cnt);

	mutex_unlock(&bpf_event_mutex);



	if (copy_to_user(&uquery->prog_cnt, &prog_cnt, sizeof(prog_cnt)) ||