[PATCH] Input: usbtouchscreen - Return directly after a failed kmalloc() in nexio_init()

[PATCH] Input: usbtouchscreen - Return directly after a failed kmalloc() in nexio_init()

[Markus Elfring]

From: Markus Elfring <elfring@users.sourceforge.net>
Date: Tue, 26 Dec 2023 21:00:25 +0100

The kfree() function was called in one case by
the nexio_init() function during error handling
even if the passed variable contained a null pointer.
This issue was detected by using the Coccinelle software.

Thus return directly after a call of the function “kmalloc” failed
at the beginning.

Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
---
 drivers/input/touchscreen/usbtouchscreen.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
index 60354ebc7242..1873c7918a78 100644
--- a/drivers/input/touchscreen/usbtouchscreen.c
+++ b/drivers/input/touchscreen/usbtouchscreen.c
@@ -977,7 +977,7 @@ static int nexio_init(struct usbtouch_usb *usbtouch)

 	buf = kmalloc(NEXIO_BUFSIZE, GFP_NOIO);
 	if (!buf)
-		goto out_buf;
+		return ret;

 	/* two empty reads */
 	for (i = 0; i < 2; i++) {
--
2.43.0

Re: [PATCH] Input: usbtouchscreen - Return directly after a failed kmalloc() in nexio_init()

[Dmitry Torokhov]

On Tue, Dec 26, 2023 at 09:08:12PM +0100, Markus Elfring wrote:
> From: Markus Elfring <elfring@users.sourceforge.net>
> Date: Tue, 26 Dec 2023 21:00:25 +0100
> 
> The kfree() function was called in one case by
> the nexio_init() function during error handling
> even if the passed variable contained a null pointer.

Which is perfectly valid thing to do, like free(), kfree() accepts NULL
argument.

> This issue was detected by using the Coccinelle software.

This tells me precisely nothing.

> 
> Thus return directly after a call of the function “kmalloc” failed
> at the beginning.

This is simply a matter of preference, the original author preferred
that style, I see no objective reason to change it.

> 
> Signed-off-by: Markus Elfring <elfring@users.sourceforge.net>
> ---
>  drivers/input/touchscreen/usbtouchscreen.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c
> index 60354ebc7242..1873c7918a78 100644
> --- a/drivers/input/touchscreen/usbtouchscreen.c
> +++ b/drivers/input/touchscreen/usbtouchscreen.c
> @@ -977,7 +977,7 @@ static int nexio_init(struct usbtouch_usb *usbtouch)
> 
>  	buf = kmalloc(NEXIO_BUFSIZE, GFP_NOIO);
>  	if (!buf)
> -		goto out_buf;
> +		return ret;
> 
>  	/* two empty reads */
>  	for (i = 0; i < 2; i++) {
> --
> 2.43.0
> 

Thanks.

-- 
Dmitry

Re: Input: usbtouchscreen - Return directly after a failed kmalloc() in nexio_init()

[Markus Elfring]

>> The kfree() function was called in one case by
>> the nexio_init() function during error handling
>> even if the passed variable contained a null pointer.
>
> Which is perfectly valid thing to do, like free(), kfree() accepts NULL argument.

I find such a function call with this special parameter not so useful.


>> Thus return directly after a call of the function “kmalloc” failed
>> at the beginning.
>
> This is simply a matter of preference, the original author preferred
> that style, I see no objective reason to change it.

Would you ever like to avoid redundant data processing a bit more?

Regards,
Markus