CVE-2026-98765USB: gadget: dummy-hcd: Fix wait for outstanding request completions

Official description

In the Linux kernel, the following vulnerability has been resolved: USB: gadget: dummy-hcd: Fix wait for outstanding request completions The dummy-hcd driver emulates synchronize_irq() by waiting until its private callback_usage counter drops to 0 (with the private lock not held). This counter is incremented whenever a gadget driver callback occurs (which requires the private lock to be dropped), but not when a request completion handler is called. This is an oversight. Request completion is triggered by timer interrupts (emulating device IRQs in a real UDC), and the interrupt handlers are supposed to have completed when the synchronize_irq() emulation routine returns -- they aren't supposed to be in the middle of a completion callback. If this happens it can lead to a gadget driver's unbind routine running before all outstanding request completions have finished, maybe even allowing the gadget driver's module to be unloaded while a completion handler is still running. Fix the oversight by incrementing the callback_usage value across request completion callbacks.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/32721319e89a2be610b0518b88f0d188ce878063
• https://git.kernel.org/stable/c/48ef54100ceffbd1a055f193873574c45f408eb5
• https://git.kernel.org/stable/c/d77cc7c0d739fb17413714c5c4914bd396502e20
• https://git.kernel.org/stable/c/6849e51b89de5b6fc7447dc8e612b58df19c7dea
• https://git.kernel.org/stable/c/7ce4dca0d53b1c3cb2b7e7bb2e42bf5db860caf2
• https://git.kernel.org/stable/c/5298c96bf0068f3160969f7ddad81976d01a9b66
• https://git.kernel.org/stable/c/3070806a7bc7bb36ed04a21022c09dafcc5619f4
• https://git.kernel.org/stable/c/b263ff9b0fc5c1f371d65c4eb196b31263d039ff