This is a note to let you know that I've just added the patch titled
iio: adis_lib: Initialize trigger before requesting interrupt
to my staging git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git in the staging-linus branch.
The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.
If you have any questions about this process, please let me know.
From f027e0b3a774e10302207e91d304bbf99e3a8b36 Mon Sep 17 00:00:00 2001
From: Lars-Peter Clausen lars@metafoo.de Date: Wed, 14 Feb 2018 15:43:00 +0100 Subject: iio: adis_lib: Initialize trigger before requesting interrupt
The adis_probe_trigger() creates a new IIO trigger and requests an interrupt associated with the trigger. The interrupt uses the generic iio_trigger_generic_data_rdy_poll() function as its interrupt handler.
Currently the driver initializes some fields of the trigger structure after the interrupt has been requested. But an interrupt can fire as soon as it has been requested. This opens up a race condition.
iio_trigger_generic_data_rdy_poll() will access the trigger data structure and dereference the ops field. If the ops field is not yet initialized this will result in a NULL pointer deref.
It is not expected that the device generates an interrupt at this point, so typically this issue did not surface unless e.g. due to a hardware misconfiguration (wrong interrupt number, wrong polarity, etc.).
But some newer devices from the ADIS family start to generate periodic interrupts in their power-on reset configuration and unfortunately the interrupt can not be masked in the device. This makes the race condition much more visible and the following crash has been observed occasionally when booting a system using the ADIS16460.
Unable to handle kernel NULL pointer dereference at virtual address 00000008 pgd = c0004000 [00000008] *pgd=00000000 Internal error: Oops: 5 [#1] PREEMPT SMP ARM Modules linked in: CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.9.0-04126-gf9739f0-dirty #257 Hardware name: Xilinx Zynq Platform task: ef04f640 task.stack: ef050000 PC is at iio_trigger_notify_done+0x30/0x68 LR is at iio_trigger_generic_data_rdy_poll+0x18/0x20 pc : [<c042d868>] lr : [<c042d924>] psr: 60000193 sp : ef051bb8 ip : 00000000 fp : ef106400 r10: c081d80a r9 : ef3bfa00 r8 : 00000087 r7 : ef051bec r6 : 00000000 r5 : ef3bfa00 r4 : ee92ab00 r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : ee97e400 Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment none Control: 18c5387d Table: 0000404a DAC: 00000051 Process swapper/0 (pid: 1, stack limit = 0xef050210) [<c042d868>] (iio_trigger_notify_done) from [<c0065b10>] (__handle_irq_event_percpu+0x88/0x118) [<c0065b10>] (__handle_irq_event_percpu) from [<c0065bbc>] (handle_irq_event_percpu+0x1c/0x58) [<c0065bbc>] (handle_irq_event_percpu) from [<c0065c30>] (handle_irq_event+0x38/0x5c) [<c0065c30>] (handle_irq_event) from [<c0068e28>] (handle_level_irq+0xa4/0x130) [<c0068e28>] (handle_level_irq) from [<c0064e74>] (generic_handle_irq+0x24/0x34) [<c0064e74>] (generic_handle_irq) from [<c021ab7c>] (zynq_gpio_irqhandler+0xb8/0x13c) [<c021ab7c>] (zynq_gpio_irqhandler) from [<c0064e74>] (generic_handle_irq+0x24/0x34) [<c0064e74>] (generic_handle_irq) from [<c0065370>] (__handle_domain_irq+0x5c/0xb4) [<c0065370>] (__handle_domain_irq) from [<c000940c>] (gic_handle_irq+0x48/0x8c) [<c000940c>] (gic_handle_irq) from [<c0013e8c>] (__irq_svc+0x6c/0xa8)
To fix this make sure that the trigger is fully initialized before requesting the interrupt.
Fixes: ccd2b52f4ac6 ("staging:iio: Add common ADIS library") Reported-by: Robin Getz Robin.Getz@analog.com Signed-off-by: Lars-Peter Clausen lars@metafoo.de Cc: Stable@vger.kernel.org Signed-off-by: Jonathan Cameron Jonathan.Cameron@huawei.com --- drivers/iio/imu/adis_trigger.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/iio/imu/adis_trigger.c b/drivers/iio/imu/adis_trigger.c index 0dd5a381be64..457372f36791 100644 --- a/drivers/iio/imu/adis_trigger.c +++ b/drivers/iio/imu/adis_trigger.c @@ -46,6 +46,10 @@ int adis_probe_trigger(struct adis *adis, struct iio_dev *indio_dev) if (adis->trig == NULL) return -ENOMEM;
+ adis->trig->dev.parent = &adis->spi->dev; + adis->trig->ops = &adis_trigger_ops; + iio_trigger_set_drvdata(adis->trig, adis); + ret = request_irq(adis->spi->irq, &iio_trigger_generic_data_rdy_poll, IRQF_TRIGGER_RISING, @@ -54,9 +58,6 @@ int adis_probe_trigger(struct adis *adis, struct iio_dev *indio_dev) if (ret) goto error_free_trig;
- adis->trig->dev.parent = &adis->spi->dev; - adis->trig->ops = &adis_trigger_ops; - iio_trigger_set_drvdata(adis->trig, adis); ret = iio_trigger_register(adis->trig);
indio_dev->trig = iio_trigger_get(adis->trig);