2022-04-01 20:20:03

by Jakob Koschel

Subject: [PATCH 1/3] ASoC: Intel: catpt: remove check of list iterator against head past the loop body

When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limiting the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
sound/soc/intel/catpt/pcm.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/sound/soc/intel/catpt/pcm.c b/sound/soc/intel/catpt/pcm.c
index a26000cd5ceb..b103b2d4026e 100644
--- a/sound/soc/intel/catpt/pcm.c
+++ b/sound/soc/intel/catpt/pcm.c
@@ -330,7 +330,8 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai,
struct catpt_stream_runtime *stream)
{
struct snd_soc_component *component = dai->component;
- struct snd_kcontrol *pos;
+ struct snd_kcontrol *pos = NULL;
+ struct snd_kcontrol *iter;
struct catpt_dev *cdev = dev_get_drvdata(dai->dev);
const char *name;
int ret;
@@ -354,12 +355,14 @@ static int catpt_dai_apply_usettings(struct snd_soc_dai *dai,
return 0;
}

- list_for_each_entry(pos, &component->card->snd_card->controls, list) {
- if (pos->private_data == component &&
- !strncmp(name, pos->id.name, sizeof(pos->id.name)))
+ list_for_each_entry(iter, &component->card->snd_card->controls, list) {
+ if (iter->private_data == component &&
+ !strncmp(name, iter->id.name, sizeof(iter->id.name))) {
+ pos = iter;
break;
+ }
}
- if (list_entry_is_head(pos, &component->card->snd_card->controls, list))
+ if (!pos)
return -ENOENT;

if (stream->template->type != CATPT_STRM_TYPE_LOOPBACK)

base-commit: f82da161ea75dc4db21b2499e4b1facd36dab275
--
2.25.1

2022-04-05 01:48:28

by Jakob Koschel

Subject: [PATCH 2/3] ASoC: sprd: remove check of list iterator against head past the loop body

When list_for_each_entry() completes the iteration over the whole list
without breaking the loop, the iterator value will be a bogus pointer
computed based on the head element.

While it is safe to use the pointer to determine if it was computed
based on the head element, either with list_entry_is_head() or
&pos->member == head, using the iterator variable after the loop should
be avoided.

In preparation to limiting the scope of a list iterator to the list
traversal loop, use a dedicated pointer to point to the found element [1].

Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1]
Signed-off-by: Jakob Koschel <[email protected]>
---
sound/soc/sprd/sprd-mcdt.c | 13 ++++++-------
1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/sound/soc/sprd/sprd-mcdt.c b/sound/soc/sprd/sprd-mcdt.c
index f6a55fa60c1b..6e27789a0df5 100644
--- a/sound/soc/sprd/sprd-mcdt.c
+++ b/sound/soc/sprd/sprd-mcdt.c
@@ -866,20 +866,19 @@ EXPORT_SYMBOL_GPL(sprd_mcdt_chan_dma_disable);
struct sprd_mcdt_chan *sprd_mcdt_request_chan(u8 channel,
enum sprd_mcdt_channel_type type)
{
- struct sprd_mcdt_chan *temp;
+ struct sprd_mcdt_chan *temp = NULL;
+ struct sprd_mcdt_chan *iter;

mutex_lock(&sprd_mcdt_list_mutex);

- list_for_each_entry(temp, &sprd_mcdt_chan_list, list) {
- if (temp->type == type && temp->id == channel) {
- list_del_init(&temp->list);
+ list_for_each_entry(iter, &sprd_mcdt_chan_list, list) {
+ if (iter->type == type && iter->id == channel) {
+ list_del_init(&iter->list);
+ temp = iter;
break;
}
}

- if (list_entry_is_head(temp, &sprd_mcdt_chan_list, list))
- temp = NULL;
-
mutex_unlock(&sprd_mcdt_list_mutex);

return temp;
--
2.25.1