CVE-2026-89733: usb: gadget: uvc: fix dangling pointers in uvc_function_bind() and uvc_function_unbind()
In the Linux kernel, the following vulnerability has been resolved:
usb: gadget: uvc: fix dangling pointers in uvcfunctionbind() and uvcfunctionunbind()
In uvcfunctionbind() error path, we use usbepfreerequest which uses uvc->controlreq but does not set it to NULL afterwards. Thus, uvc->controlreq is a dangling pointer causing a UAF. Also we do not set the uvc->controlbuf pointer to NULL after freeing it, which is another dangling pointer. Fix it by setting uvc->controlreq to NULL after we run usbepfreerequest() and uvc->controlbuf to NULL after kfree. Do the same for uvcfunctionunbind().
Affected Software
Remediation
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Configuration
Set uvc->control_req to NULL after usb_ep_free_request() and set uvc->control_buf to NULL after kfree(), in both uvc_function_bind() error handling and uvc_function_unbind().
Linux kernel USB gadget UVC uvc->control_req and uvc->control_buf = NULL
Event History
Frequently Asked Questions
What conditions are required for this issue to occur?
The issue is associated with error handling in uvc_function_bind() and cleanup in uvc_function_unbind(). It requires the USB gadget UVC function to reach code paths that free the control request or control buffer while leaving their stored pointers non-NULL.
What is the security impact of the stale pointers?
The retained uvc->control_req pointer can become a dangling pointer after usb_ep_free_request(), creating a use-after-free condition. The uvc->control_buf pointer can also remain dangling after it is freed.
What does the fix change?
The fix clears uvc->control_req after usb_ep_free_request() and clears uvc->control_buf after kfree. The same pointer cleanup is applied in both bind error handling and unbind cleanup.