[PATCH] ALSA: hda: cs35l41: fix double free in cs35l41_hda_probe()

[PATCH] ALSA: hda: cs35l41: fix double free in cs35l41_hda_probe()

[trix]

From: Tom Rix <trix@redhat.com>

Clang static analysis reports this problem
cs35l41_hda.c:501:2: warning: Attempt to free released memory
        kfree(acpi_hw_cfg);
        ^~~~~~~~~~~~~~~~~~

This second free happens in the function's error handler which
is normally ok but acpi_hw_cfg is freed in the non error case
when it is still possible to have an error.

Consolidate the frees.

Fixes: 7b2f3eb492da ("ALSA: hda: cs35l41: Add support for CS35L41 in HDA systems")
Signed-off-by: Tom Rix <trix@redhat.com>
---
 sound/pci/hda/cs35l41_hda.c | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/sound/pci/hda/cs35l41_hda.c b/sound/pci/hda/cs35l41_hda.c
index aa5bb6977792c..265ace98965f5 100644
--- a/sound/pci/hda/cs35l41_hda.c
+++ b/sound/pci/hda/cs35l41_hda.c
@@ -476,7 +476,6 @@ int cs35l41_hda_probe(struct device *dev, const char *device_name, int id, int i
 	ret = cs35l41_hda_apply_properties(cs35l41, acpi_hw_cfg);
 	if (ret)
 		goto err;
-	kfree(acpi_hw_cfg);
 
 	if (cs35l41->reg_seq->probe) {
 		ret = regmap_register_patch(cs35l41->regmap, cs35l41->reg_seq->probe,
@@ -495,13 +494,14 @@ int cs35l41_hda_probe(struct device *dev, const char *device_name, int id, int i
 
 	dev_info(cs35l41->dev, "Cirrus Logic CS35L41 (%x), Revision: %02X\n", regid, reg_revid);
 
-	return 0;
-
 err:
 	kfree(acpi_hw_cfg);
-	if (!cs35l41->vspk_always_on)
-		gpiod_set_value_cansleep(cs35l41->reset_gpio, 0);
-	gpiod_put(cs35l41->reset_gpio);
+
+	if (unlikely(ret)) {
+		if (!cs35l41->vspk_always_on)
+			gpiod_set_value_cansleep(cs35l41->reset_gpio, 0);
+		gpiod_put(cs35l41->reset_gpio);
+	}
 
 	return ret;
 }
-- 
2.26.3

Re: [PATCH] ALSA: hda: cs35l41: fix double free in cs35l41_hda_probe()

[Andy Shevchenko]

On Mon, Jan 10, 2022 at 2:37 AM Tom Rix <trix@redhat.com> wrote:
> On 1/9/22 2:33 PM, Andy Shevchenko wrote:
> On Saturday, January 8, 2022, <trix@redhat.com> wrote:

...

>> +       if (unlikely(ret)) {
>
> This is double weird. First of all, wtf unlikely is here? Second, I commented on the patch that does something with this driver and pointed out to the return 0 in some cases. This one seems a band aid.
>
> Unlikely to have an error.

We don't use likely() and unlikely() here and there, you need to
provide a very good justification of its use.

For the record, I forwarded you my review against the code where you
can find much more issues with it that are subject to fix / amend.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] ALSA: hda: cs35l41: fix double free in cs35l41_hda_probe()

[Takashi Iwai]

On Mon, 10 Jan 2022 11:21:11 +0100,
Andy Shevchenko wrote:
> 
> On Mon, Jan 10, 2022 at 2:37 AM Tom Rix <trix@redhat.com> wrote:
> > On 1/9/22 2:33 PM, Andy Shevchenko wrote:
> > On Saturday, January 8, 2022, <trix@redhat.com> wrote:
> 
> ...
> 
> >> +       if (unlikely(ret)) {
> >
> > This is double weird. First of all, wtf unlikely is here? Second, I commented on the patch that does something with this driver and pointed out to the return 0 in some cases. This one seems a band aid.
> >
> > Unlikely to have an error.
> 
> We don't use likely() and unlikely() here and there, you need to
> provide a very good justification of its use.
> 
> For the record, I forwarded you my review against the code where you
> can find much more issues with it that are subject to fix / amend.

For this particular bug fix, Dan submitted a simpler patch and I took
it now:
  https://lore.kernel.org/r/20220111072232.GG11243@kili


thanks,

Takashi