[PATCH] wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle

[PATCH] wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle

[Navid Emamdoost]

In the implementation of i2400m_op_rfkill_sw_toggle() the allocated
buffer for cmd should be released before returning. The
documentation for i2400m_msg_to_dev() says when it returns the buffer
can be reused. Meaning cmd should be released in either case. Move
kfree(cmd) before return to be reached by all execution paths.

Fixes: 2507e6ab7a9a ("wimax: i2400: fix memory leak")
Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>
---
 drivers/net/wimax/i2400m/op-rfkill.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wimax/i2400m/op-rfkill.c b/drivers/net/wimax/i2400m/op-rfkill.c
index 8efb493ceec2..5c79f052cad2 100644
--- a/drivers/net/wimax/i2400m/op-rfkill.c
+++ b/drivers/net/wimax/i2400m/op-rfkill.c
@@ -127,12 +127,12 @@ int i2400m_op_rfkill_sw_toggle(struct wimax_dev *wimax_dev,
 			"%d\n", result);
 	result = 0;
 error_cmd:
-	kfree(cmd);
 	kfree_skb(ack_skb);
 error_msg_to_dev:
 error_alloc:
 	d_fnend(4, dev, "(wimax_dev %p state %d) = %d\n",
 		wimax_dev, state, result);
+	kfree(cmd);
 	return result;
 }
 
-- 
2.17.1

Re: [PATCH] wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle

[Markus Elfring]

> Move kfree(cmd) before return to be reached by all execution paths.

I suggest to reconsider this change suggestion once more.


> Fixes: 2507e6ab7a9a ("wimax: i2400: fix memory leak")

I find it interesting that you would like to fix your commit from 2019-09-10.
https://lore.kernel.org/patchwork/patch/1126399/

Will it be helpful to refer also to the commit 024f7f31ed15c471f80408d8b5045497e27e1135
("i2400m: Generic probe/disconnect, reset and message passing" from 2009-01-07)?


> +++ b/drivers/net/wimax/i2400m/op-rfkill.c
> @@ -127,12 +127,12 @@ int i2400m_op_rfkill_sw_toggle(struct wimax_dev *wimax_dev,
>  			"%d\n", result);
>  	result = 0;
>  error_cmd:
> -	kfree(cmd);
>  	kfree_skb(ack_skb);
>  error_msg_to_dev:
>  error_alloc:
>  	d_fnend(4, dev, "(wimax_dev %p state %d) = %d\n",
>  		wimax_dev, state, result);
> +	kfree(cmd);
>  	return result;
>  }


I would prefer to improve the exception handling like the following.
(Would you like to avoid passing a null pointer at the end?)

-error_cmd:
+free_skb:
-	kfree(cmd);
 	kfree_skb(ack_skb);
-error_msg_to_dev:
+free_cmd:
+	kfree(cmd);
-error_alloc:
+exit:


How do you think about this update variant?

Regards,
Markus

Re: [PATCH] wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle

[Markus Elfring]

> Move kfree(cmd) before return to be reached by all execution paths.

I suggest to reconsider this change suggestion once more.


> Fixes: 2507e6ab7a9a ("wimax: i2400: fix memory leak")

I find it interesting that you would like to fix your commit from 2019-09-10.
https://lore.kernel.org/patchwork/patch/1126399/

Will it be helpful to refer also to the commit 024f7f31ed15c471f80408d8b5045497e27e1135
("i2400m: Generic probe/disconnect, reset and message passing" from 2009-01-07)?


> +++ b/drivers/net/wimax/i2400m/op-rfkill.c
> @@ -127,12 +127,12 @@ int i2400m_op_rfkill_sw_toggle(struct wimax_dev *wimax_dev,
>  			"%d\n", result);
>  	result = 0;
>  error_cmd:
> -	kfree(cmd);
>  	kfree_skb(ack_skb);
>  error_msg_to_dev:
>  error_alloc:
>  	d_fnend(4, dev, "(wimax_dev %p state %d) = %d\n",
>  		wimax_dev, state, result);
> +	kfree(cmd);
>  	return result;
>  }


I would prefer to improve the exception handling like the following.
(Would you like to avoid passing a null pointer at the end?)

-error_cmd:
+free_skb:
-	kfree(cmd);
 	kfree_skb(ack_skb);
-error_msg_to_dev:
+free_cmd:
+	kfree(cmd);
-error_alloc:
+exit:


How do you think about this update variant?

Regards,
Markus

Re: [PATCH] wimax: i2400: Fix memory leak in i2400m_op_rfkill_sw_toggle

[David Miller]

From: Navid Emamdoost <navid.emamdoost@gmail.com>
Date: Fri, 25 Oct 2019 23:53:30 -0500

> In the implementation of i2400m_op_rfkill_sw_toggle() the allocated
> buffer for cmd should be released before returning. The
> documentation for i2400m_msg_to_dev() says when it returns the buffer
> can be reused. Meaning cmd should be released in either case. Move
> kfree(cmd) before return to be reached by all execution paths.
> 
> Fixes: 2507e6ab7a9a ("wimax: i2400: fix memory leak")
> Signed-off-by: Navid Emamdoost <navid.emamdoost@gmail.com>

Applied.