CVE-2026-98773
Description
In the Linux kernel, the following vulnerability has been resolved:
USB: cdc-acm: skip URB restart in port_shutdown if disconnected
acm_port_shutdown() is called from the tty-port machinery whenever the
last user closes the port. acm_disconnect() sets acm->disconnected and
calls tty_port_tty_vhangup(), which eventually triggers port_shutdown().
At that point acm_disconnect() has already called acm_poison_urbs() and
is about to free the control and read URBs.
However, acm_port_shutdown() unconditionally calls acm_unpoison_urbs()
and, when the ALWAYS_POLL_CTRL quirk is set, immediately re-submits the
ctrlurb and all read URBs. If the concurrent acm_disconnect() then
frees those URBs and their DMA buffers while they are in-flight, the
result is a use-after-free in acm_ctrl_irq() or acm_read_bulk_callback()
accessing the freed DMA memory.
Fix by checking acm->disconnected after draining the delayed anchor and
returning early: if we are in a disconnect path the URBs must remain
poisoned and must not be resubmitted.
The early return is placed after the delayed-anchor drain loop because
that loop only cancels write-side accounting (wb->use = false and
autopm counter) and does not touch the hardware path.
EPSS (Exploit Prediction Scoring System)
EPSS (Exploit Prediction Scoring System)
Prevede la probabilità di sfruttamento basata su intelligence sulle minacce e sulle caratteristiche della vulnerabilità.