Unverified Commit 8d2e0cb3 authored by Johan Hovold's avatar Johan Hovold Committed by Mark Brown
Browse files

spi: fix use-after-free on managed registration failure 



The SPI API is asymmetric and the controller is freed as part of
deregistration (unless it has been allocated using
devm_spi_alloc_host/target()).

A recent change converting the managed registration function to use
devm_add_action_or_reset() inadvertently introduced a (mostly
theoretical) regression where a non-devres managed controller could be
freed as part of failed registration. This in turn would lead to
use-after-free in controller driver error paths.

Fix this by taking another reference before calling
devm_add_action_or_reset() and not releasing it on errors for
non-devres allocated controllers.

An alternative would be a partial revert of the offending commit, but
it is better to handle this explicitly until the API has been fixed
(e.g. see 5e844cc3 ("spi: Introduce device-managed SPI controller
allocation")).

Fixes: b6376dbe ("spi: Simplify devm_spi_*_controller()")
Reported-by: default avatarFelix Gu <ustc.gu@gmail.com>
Link: https://lore.kernel.org/all/20260324145548.139952-1-ustc.gu@gmail.com/


Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: default avatarJohan Hovold <johan@kernel.org>
Acked-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patch.msgid.link/20260325145319.1132072-1-johan@kernel.org


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent cc34d77d

drivers/spi/spi.c

+12 −1
Original line number Diff line number Diff line
@@ -3534,8 +3534,19 @@ int devm_spi_register_controller(struct device *dev, 
	if (ret)

		return ret;



	return devm_add_action_or_reset(dev, devm_spi_unregister_controller, ctlr);

	/*

	 * Prevent controller from being freed by spi_unregister_controller()

	 * if devm_add_action_or_reset() fails for a non-devres allocated

	 * controller.

	 */

	spi_controller_get(ctlr);



	ret = devm_add_action_or_reset(dev, devm_spi_unregister_controller, ctlr);



	if (ret == 0 || ctlr->devm_allocated)

		spi_controller_put(ctlr);



	return ret;

}

EXPORT_SYMBOL_GPL(devm_spi_register_controller);