[PATCH] spi: tegra20-slink: fix UAF in tegra_slink_remove()

[PATCH] spi: tegra20-slink: fix UAF in tegra_slink_remove()

[Yang Yingliang]

After calling spi_unregister_master(), the refcount of master will
be decrease to 0, and it will be freed in spi_controller_release(),
the device data also will be freed, so it will lead a UAF when using
'tspi'. To fix this, get the master before unregister and put it when
finish using it.

Fixes: 26c863418221 ("spi: tegra20-slink: Don't use resource-managed spi_register helper")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
 drivers/spi/spi-tegra20-slink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c
index 38360434d6e9..148043d0c2b8 100644
--- a/drivers/spi/spi-tegra20-slink.c
+++ b/drivers/spi/spi-tegra20-slink.c
@@ -1136,7 +1136,7 @@ static int tegra_slink_probe(struct platform_device *pdev)
 
 static int tegra_slink_remove(struct platform_device *pdev)
 {
-	struct spi_master *master = platform_get_drvdata(pdev);
+	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
 	struct tegra_slink_data	*tspi = spi_master_get_devdata(master);
 
 	spi_unregister_master(master);
@@ -1151,6 +1151,7 @@ static int tegra_slink_remove(struct platform_device *pdev)
 	if (tspi->rx_dma_chan)
 		tegra_slink_deinit_dma_param(tspi, true);
 
+	spi_master_put(master);
 	return 0;
 }
 
-- 
2.25.1

Re: [PATCH] spi: tegra20-slink: fix UAF in tegra_slink_remove()

[Mark Brown]

On Wed, 13 Jul 2022 17:40:23 +0800, Yang Yingliang wrote:
> After calling spi_unregister_master(), the refcount of master will
> be decrease to 0, and it will be freed in spi_controller_release(),
> the device data also will be freed, so it will lead a UAF when using
> 'tspi'. To fix this, get the master before unregister and put it when
> finish using it.
> 
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: tegra20-slink: fix UAF in tegra_slink_remove()
      commit: 7e9984d183bb1e99e766c5c2b950ff21f7f7b6c0

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark