[PATCH 4.14 001/242] spi: bcm2835aux: Fix use-after-free on unbind

Greg Kroah-Hartman
2020-12-28T16:29:00Z

From: Lukas Wunner <lukas@wunner.de>

[ 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/b290b06357d0c0bdee9cecc539b840a90630f101.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/spi/spi-bcm2835aux.c | 18 ++++++------------
1 file changed, 6 insertions(+), 12 deletions(-)

--- a/drivers/spi/spi-bcm2835aux.c
+++ b/drivers/spi/spi-bcm2835aux.c
@@ -407,7 +407,7 @@ static int bcm2835aux_spi_probe(struct p
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 +439,26 @@ static int bcm2835aux_spi_probe(struct p
/* 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 PTR_ERR(bs->clk);
}

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 +491,6 @@ static int bcm2835aux_spi_probe(struct p

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