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FROMGIT: usb: dwc3: gadget: Free gadget structure only after freeing endpoints

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As part of commit e81a7018d9 ("usb: dwc3: allocate gadget structure
dynamically") the dwc3_gadget_release() was added which will free
the dwc->gadget structure upon the device's removal when
usb_del_gadget_udc() is called in dwc3_gadget_exit().

However, simply freeing the gadget results a dangling pointer
situation: the endpoints created in dwc3_gadget_init_endpoints()
have their dep->endpoint.ep_list members chained off the list_head
anchored at dwc->gadget->ep_list.  Thus when dwc->gadget is freed,
the first dwc3_ep in the list now has a dangling prev pointer and
likewise for the next pointer of the dwc3_ep at the tail of the list.
The dwc3_gadget_free_endpoints() that follows will result in a
use-after-free when it calls list_del().

This was caught by enabling KASAN and performing a driver unbind.
The recent commit 568262bf54 ("usb: dwc3: core: Add shutdown
callback for dwc3") also exposes this as a panic during shutdown.

There are a few possibilities to fix this.  One could be to perform
a list_del() of the gadget->ep_list itself which removes it from
the rest of the dwc3_ep chain.

Another approach is what this patch does, by splitting up the
usb_del_gadget_udc() call into its separate "del" and "put"
components.  This allows dwc3_gadget_free_endpoints() to be
called before the gadget is finally freed with usb_put_gadget().

Fixes: e81a7018d9 ("usb: dwc3: allocate gadget structure dynamically")
Reviewed-by: Peter Chen <peter.chen@kernel.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>
Link: https://lore.kernel.org/r/20210501093558.7375-1-jackp@codeaurora.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit bb9c74a5bd
 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-linus)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I0062f1ccdda604938d8e2f68de4ae27360397d9f
This commit is contained in:
Jack Pham 2021-05-01 02:35:58 -07:00 • committed by Greg Kroah-Hartman
commit c3f92e5f6c
1 changed files with 2 additions and 1 deletions
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3
drivers/usb/dwc3/gadget.c
View file

@ -4086,8 +4086,9 @@ err0:
void dwc3_gadget_exit(struct dwc3 *dwc)
{
usb_del_gadget_udc(dwc->gadget);
usb_del_gadget(dwc->gadget);
dwc3_gadget_free_endpoints(dwc);
usb_put_gadget(dwc->gadget);
dma_free_coherent(dwc->sysdev, DWC3_BOUNCE_SIZE, dwc->bounce,
dwc->bounce_addr);
kfree(dwc->setup_buf);