CVE-2026-98752tty: port: fix tty_port_tty_vhangup() race

Official description

In the Linux kernel, the following vulnerability has been resolved: tty: port: fix tty_port_tty_vhangup() race Drivers rely on tty_port_tty_vhangup() to synchronously hang up their ports before tearing down resources as part of deregistration (e.g. on physical disconnect). If tty_port_tty_vhangup() races with another hangup it may however return before the port has been shut down. This is in turn can lead to use-after-free and NULL-pointer dereferences in racing ioctls (including a synchronous hangup) and in processing of racing asynchronous hangups (carrier loss). Add the missing serialisation to tty_port_tty_vhangup() and tty_port_hangup() so that the former does not return until the port has been shut down also when there is a racing hangup. Note that serial core does not use tty_port_hangup(), but it already holds the port mutex when clearing port->tty and shutting down the port in uart_hangup().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/a78910f6d78cc1415cbc9b4fb621c3f4f6945be2
• https://git.kernel.org/stable/c/2e16ae1464a4f435425c6f6ff1e293db850a624c
• https://git.kernel.org/stable/c/a776d603d1e1bba2837295817b0a39394707b10d
• https://git.kernel.org/stable/c/ce220b4cdf62f73db0c1940f968eb33b9899fdd0
• https://git.kernel.org/stable/c/6d1a984afc3ca477dab3e51ec806671d443ad524
• https://git.kernel.org/stable/c/6b7be3b9b857947e9c1338d4919d4ebd3b75e907
• https://git.kernel.org/stable/c/017b18addbe8dcace1a569a00d40ed1ba1e03f4c
• https://git.kernel.org/stable/c/b48820de8c1a596c5b99775524dfce73c6576c5d