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Subject[PATCH v3] spi: fsl-dspi: fix NULL pointer dereference
Date
Since commit 530b5affc675 ("spi: fsl-dspi: fix use-after-free in remove
path") this driver causes a kernel oops:

[ 1.891065] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000080
[..]
[ 2.056973] Call trace:
[ 2.059425] dspi_setup+0xc8/0x2e0
[ 2.062837] spi_setup+0xcc/0x248
[ 2.066160] spi_add_device+0xb4/0x198
[ 2.069918] of_register_spi_device+0x250/0x370
[ 2.074462] spi_register_controller+0x4f4/0x770
[ 2.079094] dspi_probe+0x5bc/0x7b0
[ 2.082594] platform_drv_probe+0x5c/0xb0
[ 2.086615] really_probe+0xec/0x3c0
[ 2.090200] driver_probe_device+0x60/0xc0
[ 2.094308] device_driver_attach+0x7c/0x88
[ 2.098503] __driver_attach+0x60/0xe8
[ 2.102263] bus_for_each_dev+0x7c/0xd0
[ 2.106109] driver_attach+0x2c/0x38
[ 2.109692] bus_add_driver+0x194/0x1f8
[ 2.113538] driver_register+0x6c/0x128
[ 2.117385] __platform_driver_register+0x50/0x60
[ 2.122105] fsl_dspi_driver_init+0x24/0x30
[ 2.126302] do_one_initcall+0x54/0x2d0
[ 2.130149] kernel_init_freeable+0x1ec/0x258
[ 2.134520] kernel_init+0x1c/0x120
[ 2.138018] ret_from_fork+0x10/0x34
[ 2.141606] Code: 97e0b11d aa0003f3 b4000680 f94006e0 (f9404000)
[ 2.147723] ---[ end trace 26cf63e6cbba33a8 ]---

This is because since this commit, the allocation of the drivers private
data is done explicitly and in this case spi_alloc_master() won't set the
correct pointer.

Also move the platform_set_drvdata() to have both next to each other.

Fixes: 530b5affc675 ("spi: fsl-dspi: fix use-after-free in remove path")
Signed-off-by: Michael Walle <michael@walle.cc>
Tested-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
---
changes since v2:
- trimmed the commit message, suggested by Krzysztof.

changes since v1:
- moved platform_set_drvdata(), suggested by Krzysztof.

drivers/spi/spi-fsl-dspi.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index a939618f5e47..3967afa465f0 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -1236,6 +1236,9 @@ static int dspi_probe(struct platform_device *pdev)
if (!ctlr)
return -ENOMEM;

+ spi_controller_set_devdata(ctlr, dspi);
+ platform_set_drvdata(pdev, dspi);
+
dspi->pdev = pdev;
dspi->ctlr = ctlr;

@@ -1371,8 +1374,6 @@ static int dspi_probe(struct platform_device *pdev)
if (dspi->devtype_data->trans_mode != DSPI_DMA_MODE)
ctlr->ptp_sts_supported = true;

- platform_set_drvdata(pdev, dspi);
-
ret = spi_register_controller(ctlr);
if (ret != 0) {
dev_err(&pdev->dev, "Problem registering DSPI ctlr\n");
--
2.20.1
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