[PATCH] spi: Fix reference count leak in slave_show()

[PATCH] spi: Fix reference count leak in slave_show()

[Miaoqian Lin]

Fix a reference count leak in slave_show() by properly putting the device
reference obtained from device_find_any_child().

Fixes: 6c364062bfed ("spi: core: Add support for registering SPI slave controllers")
Fixes: c21b0837983d ("spi: Use device_find_any_child() instead of custom approach")
Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
---
 drivers/spi/spi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index a7a4647717d4..ff07c87dbadc 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -2954,9 +2954,13 @@ static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
 	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
 						   dev);
 	struct device *child;
+	int ret;
 
 	child = device_find_any_child(&ctlr->dev);
-	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
+	ret = sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
+	put_device(child);
+
+	return ret;
 }
 
 static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
-- 
2.39.5 (Apple Git-154)

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Geert Uytterhoeven]

On Wed, 19 Mar 2025 at 04:23, Miaoqian Lin <linmq006@gmail.com> wrote:
> Fix a reference count leak in slave_show() by properly putting the device
> reference obtained from device_find_any_child().
>
> Fixes: 6c364062bfed ("spi: core: Add support for registering SPI slave controllers")
> Fixes: c21b0837983d ("spi: Use device_find_any_child() instead of custom approach")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Andy Shevchenko]

On Wed, Mar 19, 2025 at 11:23:04AM +0800, Miaoqian Lin wrote:
> Fix a reference count leak in slave_show() by properly putting the device
> reference obtained from device_find_any_child().

...

>  	struct device *child;
> +	int ret;
>  
>  	child = device_find_any_child(&ctlr->dev);
> -	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> +	ret = sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> +	put_device(child);
> +
> +	return ret;

Can be written better in case of NULL:

	child = device_find_any_child(&ctlr->dev);
	if (child)
		return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias);

	put_device(child);
	return sysfs_emit(buf, "%s\n", NULL);

No variable needed.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Andy Shevchenko]

On Wed, Mar 19, 2025 at 12:44:33PM +0200, Andy Shevchenko wrote:
> On Wed, Mar 19, 2025 at 11:23:04AM +0800, Miaoqian Lin wrote:

...

> >  	struct device *child;
> > +	int ret;
> >  
> >  	child = device_find_any_child(&ctlr->dev);
> > -	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> > +	ret = sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> > +	put_device(child);
> > +
> > +	return ret;
> 
> Can be written better in case of NULL:
> 
> 	child = device_find_any_child(&ctlr->dev);
> 	if (child)
> 		return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias);

Of course this has to be

		return sysfs_emit(buf, "%s\n", to_spi_device(child)->modalias);

> 
> 	put_device(child);
> 	return sysfs_emit(buf, "%s\n", NULL);
> 
> No variable needed.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Andy Shevchenko]

On Wed, Mar 19, 2025 at 12:45:03PM +0200, Andy Shevchenko wrote:
> On Wed, Mar 19, 2025 at 12:44:33PM +0200, Andy Shevchenko wrote:
> > On Wed, Mar 19, 2025 at 11:23:04AM +0800, Miaoqian Lin wrote:

...

> > >  	struct device *child;
> > > +	int ret;
> > >  
> > >  	child = device_find_any_child(&ctlr->dev);
> > > -	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> > > +	ret = sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> > > +	put_device(child);
> > > +
> > > +	return ret;
> > 
> > Can be written better in case of NULL:
> > 
> > 	child = device_find_any_child(&ctlr->dev);
> > 	if (child)
> > 		return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias);
> 
> Of course this has to be
> 
> 		return sysfs_emit(buf, "%s\n", to_spi_device(child)->modalias);

And I mixed the conditional, but I hope you got the idea...

> > 
> > 	put_device(child);
> > 	return sysfs_emit(buf, "%s\n", NULL);
> > 
> > No variable needed.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Greg Kroah-Hartman]

On Wed, Mar 19, 2025 at 11:23:04AM +0800, Miaoqian Lin wrote:
> Fix a reference count leak in slave_show() by properly putting the device
> reference obtained from device_find_any_child().
> 
> Fixes: 6c364062bfed ("spi: core: Add support for registering SPI slave controllers")
> Fixes: c21b0837983d ("spi: Use device_find_any_child() instead of custom approach")
> Signed-off-by: Miaoqian Lin <linmq006@gmail.com>
> ---
>  drivers/spi/spi.c | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
> index a7a4647717d4..ff07c87dbadc 100644
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -2954,9 +2954,13 @@ static ssize_t slave_show(struct device *dev, struct device_attribute *attr,
>  	struct spi_controller *ctlr = container_of(dev, struct spi_controller,
>  						   dev);
>  	struct device *child;
> +	int ret;
>  
>  	child = device_find_any_child(&ctlr->dev);
> -	return sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> +	ret = sysfs_emit(buf, "%s\n", child ? to_spi_device(child)->modalias : NULL);
> +	put_device(child);
> +
> +	return ret;
>  }
>  
>  static ssize_t slave_store(struct device *dev, struct device_attribute *attr,
> -- 
> 2.39.5 (Apple Git-154)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
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created.  Hopefully you will not take offence and will fix the problem
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You are receiving this message because of the following common error(s)
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If you wish to discuss this problem further, or you have questions about
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thanks,

greg k-h's patch email bot

Re: [PATCH] spi: Fix reference count leak in slave_show()

[Mark Brown]

On Wed, 19 Mar 2025 11:23:04 +0800, Miaoqian Lin wrote:
> Fix a reference count leak in slave_show() by properly putting the device
> reference obtained from device_find_any_child().
> 
> 

Applied to

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

Thanks!

[1/1] spi: Fix reference count leak in slave_show()
      commit: 176fda56d72a267731f82aa4a3aeca430394f10e

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
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Thanks,
Mark