[PATCH v2 0/4] serial: fix console lifetime bugs on failed bind and removal

[Karl Mehltretter <kmehltretter@gmail.com>]

This series fixes three serial/tty bind-error bugs and an i.MX console
port-table lifetime bug. The fixes were found with failslab fail-nth sweeps
and sysfs bind/unbind sequences under KASAN on QEMU's raspi1ap and
mcimx6ul-evk machines.

Patches 1-3 fix shared serial/tty core code. Patch 1 moves fallible serial
core allocations before console registration; patch 2 clears serial-core
pointers after uart_driver registration fails; and patch 3 makes a non-NULL
tty cdev slot mean that the cdev is live.

Patch 4 clears i.MX's devm-allocated port-table entry on probe failure and
removal. It keeps the entry valid through console unregistration and
serializes the table updates against sibling probes.

Backporting note: the probe-failure half of patch 4 relies on patch 1, which
ensures that uart_add_one_port() cannot fail after registering the console.
For complete coverage, patches 1 and 4 should be backported together.

Validation for patch 4 includes reproducing the sibling-probe race under
KASAN with and without the fix, a sequential unbind/rebind regression, and
the same test with CONFIG_PROVE_LOCKING=y. The fixed kernel keeps the
console unregistered and survives an explicit printk in each applicable run.

Changes in v2:
- Patch 4: serialize port registration and removal with imx_uart_ports[]
  updates to close the reported sibling-probe race.
- Patches 1-3 are unchanged.

v1: https://lore.kernel.org/r/20260719160812.35407-1-kmehltretter@gmail.com

Karl Mehltretter (4):
  serial: core: do fallible allocations before the console can be
    registered
  serial: core: clear freed pointers on uart_register_driver() failure
  tty: don't oops in tty_unregister_device() when no cdev is registered
  serial: imx: serialize imx_uart_ports[] lifetime

 drivers/tty/serial/imx.c         | 21 ++++++++++++++++++--
 drivers/tty/serial/serial_core.c | 33 ++++++++++++++++++--------------
 drivers/tty/tty_io.c             |  6 ++++--
 3 files changed, 42 insertions(+), 18 deletions(-)

-- 
2.53.0