[PATCH] spi: s3c64xx: fix NULL-deref on driver unbind

[PATCH] spi: s3c64xx: fix NULL-deref on driver unbind

[Johan Hovold]

A change moving DMA channel allocation from probe() back to
s3c64xx_spi_prepare_transfer() failed to remove the corresponding
deallocation from remove().

Drop the bogus DMA channel release from remove() to avoid triggering a
NULL-pointer dereference on driver unbind.

This issue was flagged by Sashiko when reviewing a controller
deregistration fix.

Fixes: f52b03c70744 ("spi: s3c64xx: requests spi-dma channel only during data transfer")
Cc: stable@vger.kernel.org	# 6.0
Cc: Adithya K V <adithya.kv@samsung.com>
Link: https://sashiko.dev/#/patchset/20260410081757.503099-1-johan%40kernel.org
Signed-off-by: Johan Hovold <johan@kernel.org>
---

Note that this one should be applied on top of the deregistration fixes:

	https://lore.kernel.org/lkml/20260410081757.503099-1-johan@kernel.org/

to avoid a (trivial) conflict if applied in reverse order.

Johan


 drivers/spi/spi-s3c64xx.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/spi/spi-s3c64xx.c b/drivers/spi/spi-s3c64xx.c
index 95b61264b679..37176e557099 100644
--- a/drivers/spi/spi-s3c64xx.c
+++ b/drivers/spi/spi-s3c64xx.c
@@ -1403,11 +1403,6 @@ static void s3c64xx_spi_remove(struct platform_device *pdev)
 
 	writel(0, sdd->regs + S3C64XX_SPI_INT_EN);
 
-	if (!is_polling(sdd)) {
-		dma_release_channel(sdd->rx_dma.ch);
-		dma_release_channel(sdd->tx_dma.ch);
-	}
-
 	pm_runtime_put_noidle(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);
 	pm_runtime_set_suspended(&pdev->dev);
-- 
2.52.0

Re: [PATCH] spi: s3c64xx: fix NULL-deref on driver unbind

[Mark Brown]

On Fri, 10 Apr 2026 11:49:25 +0200, Johan Hovold wrote:
> spi: s3c64xx: fix NULL-deref on driver unbind

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-7.1

Thanks!

[1/1] spi: s3c64xx: fix NULL-deref on driver unbind
      https://git.kernel.org/broonie/spi/c/45daacbead8a

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