2021-04-19 22:18:59

by Wesley Cheng

Subject: [PATCH] usb: gadget: Fix double free of device descriptor pointers

From: Hemant Kumar <[email protected]>

Upon driver unbind usb_free_all_descriptors() function frees all
speed descriptor pointers without setting them to NULL. In case
gadget speed changes (i.e from super speed plus to super speed)
after driver unbind only upto super speed descriptor pointers get
populated. Super speed plus desc still holds the stale (already
freed) pointer. Fix this issue by setting all descriptor pointers
to NULL after freeing them in usb_free_all_descriptors().

Signed-off-by: Hemant Kumar <[email protected]>
Signed-off-by: Wesley Cheng <[email protected]>
---
drivers/usb/gadget/config.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c
index 2d11535..8bb2577 100644
--- a/drivers/usb/gadget/config.c
+++ b/drivers/usb/gadget/config.c
@@ -194,9 +194,13 @@ EXPORT_SYMBOL_GPL(usb_assign_descriptors);
void usb_free_all_descriptors(struct usb_function *f)
{
usb_free_descriptors(f->fs_descriptors);
+ f->fs_descriptors = NULL;
usb_free_descriptors(f->hs_descriptors);
+ f->hs_descriptors = NULL;
usb_free_descriptors(f->ss_descriptors);
+ f->ss_descriptors = NULL;
usb_free_descriptors(f->ssp_descriptors);
+ f->ssp_descriptors = NULL;
}
EXPORT_SYMBOL_GPL(usb_free_all_descriptors);

--
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a Linux Foundation Collaborative Project

2021-04-20 00:59:30

by Peter Chen

Subject: Re: [PATCH] usb: gadget: Fix double free of device descriptor pointers

On 21-04-19 12:57:20, Wesley Cheng wrote:
> From: Hemant Kumar <[email protected]>
>
> Upon driver unbind usb_free_all_descriptors() function frees all
> speed descriptor pointers without setting them to NULL. In case
> gadget speed changes (i.e from super speed plus to super speed)
> after driver unbind only upto super speed descriptor pointers get
> populated. Super speed plus desc still holds the stale (already
> freed) pointer. Fix this issue by setting all descriptor pointers
> to NULL after freeing them in usb_free_all_descriptors().
>
> Signed-off-by: Hemant Kumar <[email protected]>
> Signed-off-by: Wesley Cheng <[email protected]>
> ---
> drivers/usb/gadget/config.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/drivers/usb/gadget/config.c b/drivers/usb/gadget/config.c
> index 2d11535..8bb2577 100644
> --- a/drivers/usb/gadget/config.c
> +++ b/drivers/usb/gadget/config.c
> @@ -194,9 +194,13 @@ EXPORT_SYMBOL_GPL(usb_assign_descriptors);
> void usb_free_all_descriptors(struct usb_function *f)
> {
> usb_free_descriptors(f->fs_descriptors);
> + f->fs_descriptors = NULL;
> usb_free_descriptors(f->hs_descriptors);
> + f->hs_descriptors = NULL;
> usb_free_descriptors(f->ss_descriptors);
> + f->ss_descriptors = NULL;
> usb_free_descriptors(f->ssp_descriptors);
> + f->ssp_descriptors = NULL;
> }
> EXPORT_SYMBOL_GPL(usb_free_all_descriptors);
>

Reviewed-by: Peter Chen <[email protected]>

You may add Fixed-by tag, and cc to stable tree.

--

Thanks,
Peter Chen