On Mon, Nov 23, 2020 at 09:54:04AM +0100, gregkh@linuxfoundation.org wrote:

The patch below does not apply to the 4.19-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.

Below please find the backport of e13ee6cc4781 to linux-4.19.y.

Be aware that it depends on commit 5e844cc37a5c ("spi: Introduce device-managed SPI controller allocation").

Thanks!

-- >8 -- Subject: [PATCH] spi: bcm2835aux: Fix use-after-free on unbind

[ Upstream commit e13ee6cc4781edaf8c7321bee19217e3702ed481 ]

bcm2835aux_spi_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: b9dd3f6d4172 ("spi: bcm2835aux: Fix controller unregister order") Signed-off-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v4.4+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation Cc: stable@vger.kernel.org # v4.4+: b9dd3f6d4172: spi: bcm2835aux: Fix controller unregister order Cc: stable@vger.kernel.org # v4.4+ Link: https://lore.kernel.org/r/b290b06357d0c0bdee9cecc539b840a90630f101.160512103... Signed-off-by: Mark Brown broonie@kernel.org --- drivers/spi/spi-bcm2835aux.c | 17 ++++++----------- 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/drivers/spi/spi-bcm2835aux.c b/drivers/spi/spi-bcm2835aux.c index 11895c98aae3..8ea7e31b8c2f 100644 --- a/drivers/spi/spi-bcm2835aux.c +++ b/drivers/spi/spi-bcm2835aux.c @@ -407,7 +407,7 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) unsigned long clk_hz; int err;

- master = spi_alloc_master(&pdev->dev, sizeof(*bs)); + master = devm_spi_alloc_master(&pdev->dev, sizeof(*bs)); if (!master) { dev_err(&pdev->dev, "spi_alloc_master() failed\n"); return -ENOMEM; @@ -439,30 +439,27 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev) /* the main area */ res = platform_get_resource(pdev, IORESOURCE_MEM, 0); bs->regs = devm_ioremap_resource(&pdev->dev, res); - if (IS_ERR(bs->regs)) { - err = PTR_ERR(bs->regs); - goto out_master_put; - } + if (IS_ERR(bs->regs)) + return PTR_ERR(bs->regs);

bs->clk = devm_clk_get(&pdev->dev, NULL); if ((!bs->clk) || (IS_ERR(bs->clk))) { err = PTR_ERR(bs->clk); dev_err(&pdev->dev, "could not get clk: %d\n", err); - goto out_master_put; + return err; }

bs->irq = platform_get_irq(pdev, 0); if (bs->irq <= 0) { dev_err(&pdev->dev, "could not get IRQ: %d\n", bs->irq); - err = bs->irq ? bs->irq : -ENODEV; - goto out_master_put; + return bs->irq ? bs->irq : -ENODEV; }

/* this also enables the HW block */ err = clk_prepare_enable(bs->clk); if (err) { dev_err(&pdev->dev, "could not prepare clock: %d\n", err); - goto out_master_put; + return err; }

/* just checking if the clock returns a sane value */ @@ -495,8 +492,6 @@ static int bcm2835aux_spi_probe(struct platform_device *pdev)

out_clk_disable: clk_disable_unprepare(bs->clk); -out_master_put: - spi_master_put(master); return err; }