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Subject[PATCH 5.9 003/152] spi: bcm-qspi: Fix use-after-free on unbind
Date
From: Lukas Wunner <lukas@wunner.de>

commit 63c5395bb7a9777a33f0e7b5906f2c0170a23692 upstream

bcm_qspi_remove() calls spi_unregister_master() even though
bcm_qspi_probe() calls devm_spi_register_master(). The spi_master is
therefore unregistered and freed twice on unbind.

Moreover, since commit 0392727c261b ("spi: bcm-qspi: Handle clock probe
deferral"), bcm_qspi_probe() leaks the spi_master allocation if the call
to devm_clk_get_optional() fails.

Fix by switching over to the new devm_spi_alloc_master() helper which
keeps the private data accessible until the driver has unbound and also
avoids the spi_master leak on probe.

While at it, fix an ordering issue in bcm_qspi_remove() wherein
spi_unregister_master() is called after uninitializing the hardware,
disabling the clock and freeing an IRQ data structure. The correct
order is to call spi_unregister_master() *before* those teardown steps
because bus accesses may still be ongoing until that function returns.

Fixes: fa236a7ef240 ("spi: bcm-qspi: Add Broadcom MSPI driver")
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: <stable@vger.kernel.org> # v4.9+: 123456789abc: spi: Introduce device-managed SPI controller allocation
Cc: <stable@vger.kernel.org> # v4.9+
Cc: Kamal Dasu <kdasu.kdev@gmail.com>
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/5e31a9a59fd1c0d0b795b2fe219f25e5ee855f9d.1605121038.git.lukas@wunner.de
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/spi/spi-bcm-qspi.c | 34 ++++++++++++----------------------
1 file changed, 12 insertions(+), 22 deletions(-)

--- a/drivers/spi/spi-bcm-qspi.c
+++ b/drivers/spi/spi-bcm-qspi.c
@@ -1334,7 +1334,7 @@ int bcm_qspi_probe(struct platform_devic

data = of_id->data;

- master = spi_alloc_master(dev, sizeof(struct bcm_qspi));
+ master = devm_spi_alloc_master(dev, sizeof(struct bcm_qspi));
if (!master) {
dev_err(dev, "error allocating spi_master\n");
return -ENOMEM;
@@ -1374,21 +1374,17 @@ int bcm_qspi_probe(struct platform_devic

if (res) {
qspi->base[MSPI] = devm_ioremap_resource(dev, res);
- if (IS_ERR(qspi->base[MSPI])) {
- ret = PTR_ERR(qspi->base[MSPI]);
- goto qspi_resource_err;
- }
+ if (IS_ERR(qspi->base[MSPI]))
+ return PTR_ERR(qspi->base[MSPI]);
} else {
- goto qspi_resource_err;
+ return 0;
}

res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "bspi");
if (res) {
qspi->base[BSPI] = devm_ioremap_resource(dev, res);
- if (IS_ERR(qspi->base[BSPI])) {
- ret = PTR_ERR(qspi->base[BSPI]);
- goto qspi_resource_err;
- }
+ if (IS_ERR(qspi->base[BSPI]))
+ return PTR_ERR(qspi->base[BSPI]);
qspi->bspi_mode = true;
} else {
qspi->bspi_mode = false;
@@ -1399,18 +1395,14 @@ int bcm_qspi_probe(struct platform_devic
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "cs_reg");
if (res) {
qspi->base[CHIP_SELECT] = devm_ioremap_resource(dev, res);
- if (IS_ERR(qspi->base[CHIP_SELECT])) {
- ret = PTR_ERR(qspi->base[CHIP_SELECT]);
- goto qspi_resource_err;
- }
+ if (IS_ERR(qspi->base[CHIP_SELECT]))
+ return PTR_ERR(qspi->base[CHIP_SELECT]);
}

qspi->dev_ids = kcalloc(num_irqs, sizeof(struct bcm_qspi_dev_id),
GFP_KERNEL);
- if (!qspi->dev_ids) {
- ret = -ENOMEM;
- goto qspi_resource_err;
- }
+ if (!qspi->dev_ids)
+ return -ENOMEM;

for (val = 0; val < num_irqs; val++) {
irq = -1;
@@ -1491,7 +1483,7 @@ int bcm_qspi_probe(struct platform_devic
qspi->xfer_mode.addrlen = -1;
qspi->xfer_mode.hp = -1;

- ret = devm_spi_register_master(&pdev->dev, master);
+ ret = spi_register_master(master);
if (ret < 0) {
dev_err(dev, "can't register master\n");
goto qspi_reg_err;
@@ -1504,8 +1496,6 @@ qspi_reg_err:
clk_disable_unprepare(qspi->clk);
qspi_probe_err:
kfree(qspi->dev_ids);
-qspi_resource_err:
- spi_master_put(master);
return ret;
}
/* probe function to be called by SoC specific platform driver probe */
@@ -1515,10 +1505,10 @@ int bcm_qspi_remove(struct platform_devi
{
struct bcm_qspi *qspi = platform_get_drvdata(pdev);

+ spi_unregister_master(qspi->master);
bcm_qspi_hw_uninit(qspi);
clk_disable_unprepare(qspi->clk);
kfree(qspi->dev_ids);
- spi_unregister_master(qspi->master);

return 0;
}

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