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spi: fix use-after-free of the add_lock mutex

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commit 6c53b45c71b4920b5e62f0ea8079a1da382b9434 upstream.

Commit 6098475d4cb4 ("spi: Fix deadlock when adding SPI controllers on
SPI buses") introduced a per-controller mutex. But mutex_unlock() of
said lock is called after the controller is already freed:

  spi_unregister_controller(ctlr)
  -> put_device(&ctlr->dev)
    -> spi_controller_release(dev)
  -> mutex_unlock(&ctrl->add_lock)

Move the put_device() after the mutex_unlock().

Fixes: 6098475d4cb4 ("spi: Fix deadlock when adding SPI controllers on SPI buses")
Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Lukas Wunner <lukas@wunner.de>
Cc: stable@vger.kernel.org # v5.15
Link: https://lore.kernel.org/r/20211111083713.3335171-1-michael@walle.cc
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Michael Walle 2021-11-11 09:37:13 +01:00 • committed by Greg Kroah-Hartman
parent aa3f3d7bef
commit 54c2c96eaf
1 changed files with 6 additions and 6 deletions
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12
drivers/spi/spi.c
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@ -2670,12 +2670,6 @@ void spi_unregister_controller(struct spi_controller *ctlr)
device_del(&ctlr->dev);
/* Release the last reference on the controller if its driver
* has not yet been converted to devm_spi_alloc_master/slave().
*/
if (!ctlr->devm_allocated)
put_device(&ctlr->dev);
/* free bus id */
mutex_lock(&board_lock);
if (found == ctlr)
@ -2684,6 +2678,12 @@ void spi_unregister_controller(struct spi_controller *ctlr)
if (IS_ENABLED(CONFIG_SPI_DYNAMIC))
mutex_unlock(&ctlr->add_lock);
/* Release the last reference on the controller if its driver
* has not yet been converted to devm_spi_alloc_master/slave().
*/
if (!ctlr->devm_allocated)
put_device(&ctlr->dev);
}
EXPORT_SYMBOL_GPL(spi_unregister_controller);