linux-kernel - Re: [PATCH 2/2] USB: core: Fix potential memory leak in usb_get

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Message-ID: <20200226080906.GV32540@localhost>
Date:   Wed, 26 Feb 2020 09:09:06 +0100
From:   Johan Hovold <johan@...nel.org>
To:     Tiezhu Yang <yangtiezhu@...ngson.cn>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Xuefeng Li <lixuefeng@...ngson.cn>
Subject: Re: [PATCH 2/2] USB: core: Fix potential memory leak in
 usb_get_configuration()

On Wed, Feb 26, 2020 at 02:15:23PM +0800, Tiezhu Yang wrote:
> Make sure to free all the allocated memory before exiting from the function
> usb_get_configuration() when an error is encountered.

There's no leak in this function as far as I can tell. Any allocated
memory is released in usb_destroy_configuration() when the last
reference to the struct usb_device is dropped.

> Additionally, just initialize the variable "bigbuffer" with NULL to avoid
> the following build warning:
> 
>   CC      drivers/usb/core/config.o
> drivers/usb/core/config.c: In function ‘usb_get_configuration’:
> drivers/usb/core/config.c:956:2: warning: ‘bigbuffer’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>   kfree(bigbuffer);
>   ^

No need to mention warnings that you introduce yourself while creating
your patch. It can give the false impression that your addressing an
existing issue.

Johan