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

[Greg Kroah-Hartman]

From: Lukas Wunner <lu...@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 <lu...@wunner.de>
Cc: <sta...@vger.kernel.org> # v3.0+: 5e844cc37a5c: spi: Introduce 
device-managed SPI controller allocation
Cc: <sta...@vger.kernel.org> # v3.0+
Cc: Axel Lin <axel....@ingics.com>
Link: 
https://lore.kernel.org/r/6d97628b536baf01d5e3e39db61108f84d44c8b2.1607286887.git.lu...@wunner.de
Signed-off-by: Mark Brown <broo...@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@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;
 }