CVE-2021-46986: In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Free gadget structure only after freeing endpoints As part of commit…

PriorityP421medium5.5CVSS 3.1

AVLACLPRLUINSUCNINAH

EPSS

0.23%

13.8th percentile

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Free gadget structure only after freeing endpoints 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().

Affected

14 ranges

Vendor	Product	Version range	Fixed in
debian	linux	< linux 5.10.38-1 (bookworm)	linux 5.10.38-1 (bookworm)
linux	linux	—	—
linux	linux	>= e81a7018d93a7de31a3f121c9a7eecd0a5ec58b0 < 1ea775021282d90e1d08d696b7ab54aa75d688e5	1ea775021282d90e1d08d696b7ab54aa75d688e5
linux	linux	>= e81a7018d93a7de31a3f121c9a7eecd0a5ec58b0 < bc0cdd72493236fb72b390ad38ce581e353c143c	bc0cdd72493236fb72b390ad38ce581e353c143c
linux	linux	>= e81a7018d93a7de31a3f121c9a7eecd0a5ec58b0 < b4b8e9601d7ee8806d2687f081a42485d27674a1	b4b8e9601d7ee8806d2687f081a42485d27674a1
linux	linux	>= e81a7018d93a7de31a3f121c9a7eecd0a5ec58b0 < bb9c74a5bd1462499fe5ccb1e3c5ac40dcfa9139	bb9c74a5bd1462499fe5ccb1e3c5ac40dcfa9139
linux	linux_kernel	—	—
linux	linux_kernel	>= 0 < 5.10.38-1	5.10.38-1
linux	linux_kernel	>= 0 < 5.10.38-1	5.10.38-1
linux	linux_kernel	>= 0 < 5.10.38-1	5.10.38-1
linux	linux_kernel	>= 0 < 5.10.38-1	5.10.38-1
linux	linux_kernel	>= 5.10 < 5.10.38	5.10.38
linux	linux_kernel	>= 5.11 < 5.11.22	5.11.22
linux	linux_kernel	>= 5.12 < 5.12.5	5.12.5

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

osv5.5MEDIUM

vendor_debian5.5MEDIUM

vendor_redhat5.5MEDIUM

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