[PATCH] codecs: rt5682s: fix an incorrect NULL check on list iterator

[PATCH] codecs: rt5682s: fix an incorrect NULL check on list iterator

[Xiaomeng Tong]

The bug is here:
            if (!dai) {

The list iterator value 'dai' will *always* be set and non-NULL
by for_each_component_dais(), so it is incorrect to assume that
the iterator value will be NULL if the list is empty or no element
is found (In fact, it will be a bogus pointer to an invalid struct
object containing the HEAD). Otherwise it will bypass the check
'if (!dai) {' (never call dev_err() and never return -ENODEV;)
and lead to invalid memory access lately when calling
'rt5682s_set_bclk1_ratio(dai, factor);'.

To fix the bug, just return rt5682s_set_bclk1_ratio(dai, factor);
when found the 'dai', otherwise dev_err() and return -ENODEV;

Cc: stable@vger.kernel.org
Fixes: bdd229ab26be9 ("ASoC: rt5682s: Add driver for ALC5682I-VS codec")
Signed-off-by: Xiaomeng Tong <xiam0nd.tong@gmail.com>
---
 sound/soc/codecs/rt5682s.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/sound/soc/codecs/rt5682s.c b/sound/soc/codecs/rt5682s.c
index 1e662d1be2b3..c890e51ff953 100644
--- a/sound/soc/codecs/rt5682s.c
+++ b/sound/soc/codecs/rt5682s.c
@@ -2686,14 +2686,11 @@ static int rt5682s_bclk_set_rate(struct clk_hw *hw, unsigned long rate,
 
 	for_each_component_dais(component, dai)
 		if (dai->id == RT5682S_AIF1)
-			break;
-	if (!dai) {
-		dev_err(component->dev, "dai %d not found in component\n",
-			RT5682S_AIF1);
-		return -ENODEV;
-	}
+			return rt5682s_set_bclk1_ratio(dai, factor);
 
-	return rt5682s_set_bclk1_ratio(dai, factor);
+	dev_err(component->dev, "dai %d not found in component\n",
+		RT5682S_AIF1);
+	return -ENODEV;
 }
 
 static const struct clk_ops rt5682s_dai_clk_ops[RT5682S_DAI_NUM_CLKS] = {
-- 
2.17.1

Re: [PATCH] codecs: rt5682s: fix an incorrect NULL check on list iterator

[Mark Brown]

On Sun, 27 Mar 2022 16:13:00 +0800, Xiaomeng Tong wrote:
> The bug is here:
>             if (!dai) {
> 
> The list iterator value 'dai' will *always* be set and non-NULL
> by for_each_component_dais(), so it is incorrect to assume that
> the iterator value will be NULL if the list is empty or no element
> is found (In fact, it will be a bogus pointer to an invalid struct
> object containing the HEAD). Otherwise it will bypass the check
> 'if (!dai) {' (never call dev_err() and never return -ENODEV;)
> and lead to invalid memory access lately when calling
> 'rt5682s_set_bclk1_ratio(dai, factor);'.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git for-next

Thanks!

[1/1] codecs: rt5682s: fix an incorrect NULL check on list iterator
      commit: acc72863e0f11cd0bedc888b663700229f9ba5ff

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark