Re: FAILED: patch "[PATCH] spi: spi-geni-qcom: Fix use-after-free on unbind" failed to apply to 5.4-stable tree

[Lukas Wunner <lukas@wunner.de>]

On Mon, Dec 28, 2020 at 12:01:44PM +0100, gregkh@linuxfoundation.org wrote:
> The patch below does not apply to the 5.4-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@vger.kernel.org>.

Sorry for the delay, here's the backport of 8f96c434dfbc to v5.4-stable:

-- >8 --
From: Lukas Wunner <lukas@wunner.de>
Date: Mon, 7 Dec 2020 09:17:02 +0100
Subject: [PATCH] spi: spi-geni-qcom: Fix use-after-free on unbind

commit 8f96c434dfbc85ffa755d6634c8c1cb2233fcf24 upstream.

spi_geni_remove() accesses the driver's private data after calling
spi_unregister_master() even though that function releases the last
reference on the spi_master and thereby frees the private data.

Fix by switching over to the new devm_spi_alloc_master() helper which
keeps the private data accessible until the driver has unbound.

Fixes: 561de45f72bd ("spi: spi-geni-qcom: Add SPI driver support for GENI based QUP")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v4.20+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v4.20+
Cc: Rajendra Nayak <rnayak@codeaurora.org>
Cc: Girish Mahadevan <girishm@codeaurora.org>
Link: https://lore.kernel.org/r/dfa1d8c41b8acdfad87ec8654cd124e6e3cb3f31.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
[lukas: backport to v5.4.123]
Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
 drivers/spi/spi-geni-qcom.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/spi/spi-geni-qcom.c b/drivers/spi/spi-geni-qcom.c
index 6f3d64a1a2b3..01b53d816497 100644
--- a/drivers/spi/spi-geni-qcom.c
+++ b/drivers/spi/spi-geni-qcom.c
@@ -552,7 +552,7 @@ static int spi_geni_probe(struct platform_device *pdev)
 		return PTR_ERR(clk);
 	}
 
-	spi = spi_alloc_master(&pdev->dev, sizeof(*mas));
+	spi = devm_spi_alloc_master(&pdev->dev, sizeof(*mas));
 	if (!spi)
 		return -ENOMEM;
 
@@ -599,7 +599,6 @@ static int spi_geni_probe(struct platform_device *pdev)
 	free_irq(mas->irq, spi);
 spi_geni_probe_runtime_disable:
 	pm_runtime_disable(&pdev->dev);
-	spi_master_put(spi);
 	return ret;
 }
 
-- 
2.31.1