2019-09-19 09:44:48 +00:00
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From 0f76408d8c1cb0979f4286dd23912e6e59784b35 Mon Sep 17 00:00:00 2001
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From: DENG Qingfang <dqfext@gmail.com>
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Date: Thu, 19 Sep 2019 11:42:55 +0200
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Subject: [PATCH] spi: spi-gpio: fix crash when num-chipselects is 0
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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If an spi-gpio was specified with num-chipselects = <0> in dts, kernel will crash:
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Unable to handle kernel paging request at virtual address 32697073
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pgd = (ptrval)
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[32697073] *pgd=00000000
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Internal error: Oops: 5 [# 1] SMP ARM
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Modules linked in:
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CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.19.72 #0
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Hardware name: Generic DT based system
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PC is at validate_desc+0x28/0x80
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LR is at gpiod_direction_output+0x14/0x128
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...
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[<c0544db4>] (validate_desc) from [<c0545228>] (gpiod_direction_output+0x14/0x128)
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[<c0545228>] (gpiod_direction_output) from [<c05fa714>] (spi_gpio_setup+0x58/0x64)
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[<c05fa714>] (spi_gpio_setup) from [<c05f7258>] (spi_setup+0x12c/0x148)
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[<c05f7258>] (spi_setup) from [<c05f7330>] (spi_add_device+0xbc/0x12c)
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[<c05f7330>] (spi_add_device) from [<c05f7f74>] (spi_register_controller+0x838/0x924)
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[<c05f7f74>] (spi_register_controller) from [<c05fa494>] (spi_bitbang_start+0x108/0x120)
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[<c05fa494>] (spi_bitbang_start) from [<c05faa34>] (spi_gpio_probe+0x314/0x338)
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[<c05faa34>] (spi_gpio_probe) from [<c05a844c>] (platform_drv_probe+0x34/0x70)
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The cause is spi_gpio_setup() did not check if the spi-gpio has chipselect pins
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before setting their direction and results in derefing an invalid pointer.
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The bug is spotted in kernel 4.19.72 on OpenWrt, and does not occur in 4.14.
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There is a similar fix upstream 249e2632dcd0509b8f8f296f5aabf4d48dfd6da8.
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Ref: https://patchwork.kernel.org/patch/11150619/
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Cc: Linus Walleij <linus.walleij@linaro.org>
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Cc: stable@vger.kernel.org
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Signed-off-by: DENG Qingfang <dqfext@gmail.com>
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Signed-off-by: Petr Štetiar <ynezz@true.cz>
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---
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drivers/spi/spi-gpio.c | 10 ++++++----
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1 file changed, 6 insertions(+), 4 deletions(-)
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--- a/drivers/spi/spi-gpio.c
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+++ b/drivers/spi/spi-gpio.c
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2019-09-20 13:11:19 +00:00
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@@ -242,10 +242,12 @@ static int spi_gpio_setup(struct spi_dev
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2019-09-19 09:44:48 +00:00
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* The CS GPIOs have already been
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* initialized from the descriptor lookup.
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*/
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- cs = spi_gpio->cs_gpios[spi->chip_select];
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- if (!spi->controller_state && cs)
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- status = gpiod_direction_output(cs,
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- !(spi->mode & SPI_CS_HIGH));
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+ if (spi_gpio->has_cs) {
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+ cs = spi_gpio->cs_gpios[spi->chip_select];
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+ if (!spi->controller_state && cs)
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+ status = gpiod_direction_output(cs,
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+ !(spi->mode & SPI_CS_HIGH));
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+ }
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if (!status)
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status = spi_bitbang_setup(spi);
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