2023-12-26 20:08:42

by Markus Elfring

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

From: Markus Elfring <[email protected]>
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 <[email protected]>
---
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

2023-12-29 07:42:27

by Dmitry Torokhov

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

On Tue, Dec 26, 2023 at 09:08:12PM +0100, Markus Elfring wrote:
> From: Markus Elfring <[email protected]>
> 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 <[email protected]>
> ---
> 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

2023-12-29 08:57:18

by Markus Elfring

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

>> 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