[PATCH 4.14 25/31] spi: bcm2835: Fix use-after-free on unbind

From: Greg Kroah-Hartman
Date: Thu Dec 10 2020 - 13:49:48 EST


From: Lukas Wunner <lukas@xxxxxxxxx>

[ Upstream commit e1483ac030fb4c57734289742f1c1d38dca61e22 ]

bcm2835_spi_remove() accesses the driver's private data after calling
spi_unregister_controller() even though that function releases the last
reference on the spi_controller 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: f8043872e796 ("spi: add driver for BCM2835")
Reported-by: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Reported-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # v3.10+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@xxxxxxxxxxxxxxx> # v3.10+
Cc: Vladimir Oltean <olteanv@xxxxxxxxx>
Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Acked-by: Florian Fainelli <f.fainelli@xxxxxxxxx>
Link: https://lore.kernel.org/r/ad66e0a0ad96feb848814842ecf5b6a4539ef35c.1605121038.git.lukas@xxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/spi/spi-bcm2835.c | 15 +++++----------
1 file changed, 5 insertions(+), 10 deletions(-)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -737,7 +737,7 @@ static int bcm2835_spi_probe(struct plat
struct resource *res;
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;
@@ -759,23 +759,20 @@ static int bcm2835_spi_probe(struct plat

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 (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;
}

clk_prepare_enable(bs->clk);
@@ -803,8 +800,6 @@ static int bcm2835_spi_probe(struct plat

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