DENG Qingfang 1979af10ca kernel: 4.19: fix crash when setting up spi-gpio
If an spi-gpio was specified with num-chipselects = <0> in dts, kernel
will crash:

 Unable to handle kernel paging request at virtual address 32697073
 pgd = (ptrval)
 [32697073] *pgd=00000000
 Internal error: Oops: 5 [# 1] SMP ARM
 Modules linked in:
 CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.19.72 #0
 Hardware name: Generic DT based system
 PC is at validate_desc+0x28/0x80
 LR is at gpiod_direction_output+0x14/0x128
 ...
 [<c0544db4>] (validate_desc) from [<c0545228>] (gpiod_direction_output+0x14/0x128)
 [<c0545228>] (gpiod_direction_output) from [<c05fa714>] (spi_gpio_setup+0x58/0x64)
 [<c05fa714>] (spi_gpio_setup) from [<c05f7258>] (spi_setup+0x12c/0x148)
 [<c05f7258>] (spi_setup) from [<c05f7330>] (spi_add_device+0xbc/0x12c)
 [<c05f7330>] (spi_add_device) from [<c05f7f74>] (spi_register_controller+0x838/0x924)
 [<c05f7f74>] (spi_register_controller) from [<c05fa494>] (spi_bitbang_start+0x108/0x120)
 [<c05fa494>] (spi_bitbang_start) from [<c05faa34>] (spi_gpio_probe+0x314/0x338)
 [<c05faa34>] (spi_gpio_probe) from [<c05a844c>] (platform_drv_probe+0x34/0x70)

The cause is spi_gpio_setup() did not check if the spi-gpio has
chipselect pins before setting their direction and results in derefing
an invalid pointer.

The bug is spotted in kernel 4.19.72 and does not occur in 4.14.

There is a similar fix upstream in kernel 5.2 in commit 249e2632dcd0
("spi: gpio: Don't request CS GPIO in DT use-case").

Ref: https://patchwork.kernel.org/patch/11150619/
Signed-off-by: DENG Qingfang <dengqf6@mail2.sysu.edu.cn>
[use upstream patch, moved from hack to pending dir, commit facelift]
Signed-off-by: Petr Štetiar <ynezz@true.cz>
2019-09-19 11:53:18 +02:00
2019-09-15 22:53:01 +02:00
2019-09-15 22:53:01 +02:00
2007-02-26 01:05:09 +00:00
2016-03-20 17:29:15 +01:00
2019-07-26 08:09:16 +02:00
2019-01-22 13:29:46 +01:00

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          |__| W I R E L E S S   F R E E D O M
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To build your own firmware you need a Linux, BSD or MacOSX system (case
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