From: Johan Hovold <johan@kernel.org>
To: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Johan Hovold <johan@kernel.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org,
Xuefeng Li <lixuefeng@loongson.cn>
Subject: Re: [PATCH 2/2] USB: core: Fix potential memory leak in usb_get_configuration()
Date: Wed, 26 Feb 2020 11:12:12 +0100 [thread overview]
Message-ID: <20200226101212.GX32540@localhost> (raw)
In-Reply-To: <c7dfaa07-dd34-600d-2a69-95a65f966dfc@loongson.cn>
On Wed, Feb 26, 2020 at 04:42:55PM +0800, Tiezhu Yang wrote:
> On 02/26/2020 04:09 PM, Johan Hovold wrote:
> > 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.
>
> Yes, you are right, the allocated memory in usb_get_configuration()
> will be released in usb_destroy_configuration().
>
> By the way, is it better to release the allocated memory as early as
> possible
> in usb_get_configuration()? Just like this:
>
> diff --git a/drivers/usb/core/config.c b/drivers/usb/core/config.c
> index bb63ee0..dd4ebeb 100644
> --- a/drivers/usb/core/config.c
> +++ b/drivers/usb/core/config.c
> @@ -885,12 +885,17 @@ int usb_get_configuration(struct usb_device *dev)
>
> length = ncfg * sizeof(char *);
> dev->rawdescriptors = kzalloc(length, GFP_KERNEL);
> - if (!dev->rawdescriptors)
> + if (!dev->rawdescriptors) {
> + kfree(dev->config);
> return -ENOMEM;
> + }
No, there's no point in that. And just like your original proposal, this
would also introduce a double free.
Johan
next prev parent reply other threads:[~2020-02-26 10:12 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 6:15 [PATCH 1/2] USB: core: Fix build warning in usb_get_configuration() Tiezhu Yang
2020-02-26 6:15 ` [PATCH 2/2] USB: core: Fix potential memory leak " Tiezhu Yang
2020-02-26 8:09 ` Johan Hovold
2020-02-26 8:42 ` Tiezhu Yang
2020-02-26 10:12 ` Johan Hovold [this message]
2020-02-26 8:04 ` [PATCH 1/2] USB: core: Fix build warning " Johan Hovold
2020-02-26 8:35 ` Tiezhu Yang
2020-02-26 10:09 ` Johan Hovold
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