7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yuchao Zhang commit dc614d6bc991740d41d5a99ac7765c4b675dda88 upstream. 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. Fixes: f58752ebcb35 ("USB: cdc-acm: Add quirks for Yoga Book 9 14IAH10 INGENIC touchscreen") Cc: stable Signed-off-by: Yuchao Zhang Link: https://patch.msgid.link/20260918114309.3659635-2-ndaugoing@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-acm.c | 3 +++ 1 file changed, 3 insertions(+) --- a/drivers/usb/class/cdc-acm.c +++ b/drivers/usb/class/cdc-acm.c @@ -787,6 +787,9 @@ static void acm_port_shutdown(struct tty usb_autopm_put_interface_async(acm->control); } + if (acm->disconnected) + return; + acm_unpoison_urbs(acm); if (acm->quirks & ALWAYS_POLL_CTRL) {