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bpf: media: 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: linux-media@vger.kernel.org
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: Sean Young <sean@mess.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
This commit is contained in:
Stanislav Fomichev 2019-05-28 14:14:42 -07:00 committed by Daniel Borkmann
parent 54e9c9d4b5
commit 02205d2ed6
1 changed files with 17 additions and 13 deletions
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30
drivers/media/rc/bpf-lirc.c
View File

@ -8,6 +8,9 @@
#include <linux/bpf_lirc.h>
#include "rc-core-priv.h"
#define lirc_rcu_dereference(p) \
rcu_dereference_protected(p, lockdep_is_held(&ir_raw_handler_lock))
/*
* BPF interface for raw IR
*/
@ -136,7 +139,7 @@ const struct bpf_verifier_ops lirc_mode2_verifier_ops = {
static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
struct ir_raw_event_ctrl *raw;
int ret;
@ -154,12 +157,12 @@ static int lirc_bpf_attach(struct rc_dev *rcdev, struct bpf_prog *prog)
goto unlock;
}
if (raw->progs && bpf_prog_array_length(raw->progs) >= BPF_MAX_PROGS) {
old_array = lirc_rcu_dereference(raw->progs);
if (old_array && bpf_prog_array_length(old_array) >= BPF_MAX_PROGS) {
ret = -E2BIG;
goto unlock;
}
old_array = raw->progs;
ret = bpf_prog_array_copy(old_array, NULL, prog, &new_array);
if (ret < 0)
goto unlock;
@ -174,7 +177,7 @@ unlock:
static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
{
struct bpf_prog_array __rcu *old_array;
struct bpf_prog_array *old_array;
struct bpf_prog_array *new_array;
struct ir_raw_event_ctrl *raw;
int ret;
@ -192,7 +195,7 @@ static int lirc_bpf_detach(struct rc_dev *rcdev, struct bpf_prog *prog)
goto unlock;
}
old_array = raw->progs;
old_array = lirc_rcu_dereference(raw->progs);
ret = bpf_prog_array_copy(old_array, prog, NULL, &new_array);
/*
* Do not use bpf_prog_array_delete_safe() as we would end up
@ -223,21 +226,22 @@ void lirc_bpf_run(struct rc_dev *rcdev, u32 sample)
/*
* This should be called once the rc thread has been stopped, so there can be
* no concurrent bpf execution.
*
* Should be called with the ir_raw_handler_lock held.
*/
void lirc_bpf_free(struct rc_dev *rcdev)
{
struct bpf_prog_array_item *item;
struct bpf_prog_array *array;
if (!rcdev->raw->progs)
array = lirc_rcu_dereference(rcdev->raw->progs);
if (!array)
return;
item = rcu_dereference(rcdev->raw->progs)->items;
while (item->prog) {
for (item = array->items; item->prog; item++)
bpf_prog_put(item->prog);
item++;
}
bpf_prog_array_free(rcdev->raw->progs);
bpf_prog_array_free(array);
}
int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
@ -290,7 +294,7 @@ int lirc_prog_detach(const union bpf_attr *attr)
int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
{
__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
struct bpf_prog_array __rcu *progs;
struct bpf_prog_array *progs;
struct rc_dev *rcdev;
u32 cnt, flags = 0;
int ret;
@ -311,7 +315,7 @@ int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
if (ret)
goto put;
progs = rcdev->raw->progs;
progs = lirc_rcu_dereference(rcdev->raw->progs);
cnt = progs ? bpf_prog_array_length(progs) : 0;
if (copy_to_user(&uattr->query.prog_cnt, &cnt, sizeof(cnt))) {