[PATCH 4.9 162/175] spi: spi-sh: Fix use-after-free on unbind

Greg Kroah-Hartman
2020-12-28T16:30:27Z

From: Lukas Wunner <lukas@wunner.de>

commit e77df3eca12be4b17f13cf9f215cff248c57d98f upstream.

spi_sh_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: 680c1305e259 ("spi/spi_sh: use spi_unregister_master instead of spi_master_put in remove path")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v3.0+: 5e844cc37a5c: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v3.0+
Cc: Axel Lin <axel.lin@ingics.com>
Link: https://lore.kernel.org/r/6d97628b536baf01d5e3e39db61108f84d44c8b2.1607286887.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/spi/spi-sh.c | 13 ++++---------
1 file changed, 4 insertions(+), 9 deletions(-)

--- a/drivers/spi/spi-sh.c
+++ b/drivers/spi/spi-sh.c
@@ -450,7 +450,7 @@ static int spi_sh_probe(struct platform_
return -ENODEV;
}

- master = spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data));
+ master = devm_spi_alloc_master(&pdev->dev, sizeof(struct spi_sh_data));
if (master == NULL) {
dev_err(&pdev->dev, "spi_alloc_master error.\n");
return -ENOMEM;
@@ -468,16 +468,14 @@ static int spi_sh_probe(struct platform_
break;
default:
dev_err(&pdev->dev, "No support width\n");
- ret = -ENODEV;
- goto error1;
+ return -ENODEV;
}
ss->irq = irq;
ss->master = master;
ss->addr = devm_ioremap(&pdev->dev, res->start, resource_size(res));
if (ss->addr == NULL) {
dev_err(&pdev->dev, "ioremap error.\n");
- ret = -ENOMEM;
- goto error1;
+ return -ENOMEM;
}
INIT_LIST_HEAD(&ss->queue);
spin_lock_init(&ss->lock);
@@ -487,7 +485,7 @@ static int spi_sh_probe(struct platform_
ret = request_irq(irq, spi_sh_irq, 0, "spi_sh", ss);
if (ret < 0) {
dev_err(&pdev->dev, "request_irq error\n");
- goto error1;
+ return ret;
}

master->num_chipselect = 2;
@@ -506,9 +504,6 @@ static int spi_sh_probe(struct platform_

error3:
free_irq(irq, ss);
- error1:
- spi_master_put(master);
-
return ret;
}