From: Felipe Balbi <firstname.lastname@example.org> To: Jack Pham <email@example.com>, Greg Kroah-Hartman <firstname.lastname@example.org> Cc: email@example.com, firstname.lastname@example.org, Peter Chen <email@example.com>, Sandeep Maheswaram <firstname.lastname@example.org>, Wesley Cheng <email@example.com>, Elliot Berman <firstname.lastname@example.org>, Prasad Sodagudi <email@example.com>, Jack Pham <firstname.lastname@example.org> Subject: Re: [PATCH v2] usb: dwc3: gadget: Free gadget structure only after freeing endpoints Date: Mon, 10 May 2021 15:12:12 +0300 [thread overview] Message-ID: <email@example.com> (raw) In-Reply-To: <firstname.lastname@example.org> [-- Attachment #1: Type: text/plain, Size: 1860 bytes --] Hi, Jack Pham <email@example.com> writes: > As part of commit e81a7018d93a ("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 568262bf5492 ("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: e81a7018d93a ("usb: dwc3: allocate gadget structure dynamically") > Signed-off-by: Jack Pham <firstname.lastname@example.org> > --- > v2: Fix silly typo: usb_del_gadget_put -> usb_put_gadget (brain fart > when manually recomposing the patch) I thought I had acked this one already, looks like I missed it: Acked-by: Felipe Balbi <email@example.com> -- balbi [-- Attachment #2: signature.asc --] [-- Type: application/pgp-signature, Size: 511 bytes --]
next prev parent reply other threads:[~2021-05-10 13:29 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-01 9:30 [PATCH] " Jack Pham 2021-05-01 9:35 ` [PATCH v2] " Jack Pham 2021-05-06 16:02 ` Jack Pham 2021-05-08 6:21 ` Peter Chen 2021-05-10 12:12 ` Felipe Balbi [this message] 2021-05-01 11:48 ` [PATCH] " kernel test robot 2021-05-01 13:11 ` kernel test robot
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