[PATCH] ASoC: soc-core: check ops & auto_selectable_formats in snd_soc_dai_get_fmt() to prevent dereference error

[hariconscious@gmail.com]

From: HariKrishna Sagala <hariconscious@gmail.com>

Smatch reported an issue that "ops" could be null (see
line 174) where later "ops" is dereferenced to extract
the dai fmts, also auto_selectable_formats can also be
null.

Add a proper null check before accessing both the ptrs
to ensure a safe execution.

Signed-off-by: HariKrishna Sagala <hariconscious@gmail.com>
---
Hi,

Smatch flagged a null-pointer check in the function "snd_soc_dai_get_fmt". 
But the same validation is already performed in the earlier function call
"snd_soc_dai_get_fmt_max_priority" before calling into "snd_soc_dai_get_fmt".
While Smatch flags this, seeing it as a false positive, redundant null check 
added to make "snd_soc_dai_get_fmt" safe for independent reuse (if).

one way:
redundancy can also be removed in the line no.174

another way:
to have a null check considering independent functions

Please let me know.

Thanks.

 sound/soc/soc-dai.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-dai.c b/sound/soc/soc-dai.c
index f231b4174b5f..a1e05307067d 100644
--- a/sound/soc/soc-dai.c
+++ b/sound/soc/soc-dai.c
@@ -177,8 +177,9 @@ u64 snd_soc_dai_get_fmt(const struct snd_soc_dai *dai, int priority)
 	if (max < until)
 		until = max;
 
-	for (i = 0; i < until; i++)
-		fmt |= ops->auto_selectable_formats[i];
+	if (ops && ops->auto_selectable_formats)
+		for (i = 0; i < until; i++)
+			fmt |= ops->auto_selectable_formats[i];
 
 	return fmt;
 }

base-commit: 6548d364a3e850326831799d7e3ea2d7bb97ba08
-- 
2.43.0