serial: core: Prevent unsafe uart port access, part 1

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uart_remove_one_port() may race with every serial core operation
requiring a valid dereference of state->uart_port. In particular,
uart_remove_one_port() may unlink the uart port concurrently with
any serial core operation that may dereference same.

Ensure safe dereference for those operations that already claim
the port->mutex, and extend that guarantee for trivial cases,
such as the ioctl handlers. Introduce the uart_port_check() helper
which asserts port->mutex is held (only when lockdep is on).

For ioctls, return -EIO as if the port has been hung up (since it has).

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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Peter Hurley 2016-04-09 18:56:33 -07:00 • committed by Greg Kroah-Hartman

parent 49c02304fe

commit 4047b37122

1 changed files with 104 additions and 53 deletions

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drivers/tty/serial/serial_core.c

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