From: Ian Abbott Date: Wed, 26 Jun 2019 13:18:04 +0000 (+0100) Subject: staging: comedi: dt282x: fix a null pointer deref on interrupt X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=a1fcfe095c8c22f67aaee0eba7acfd46559b75d5;p=GitHub%2FLineageOS%2Fandroid_kernel_motorola_exynos9610.git staging: comedi: dt282x: fix a null pointer deref on interrupt commit b8336be66dec06bef518030a0df9847122053ec5 upstream. The interrupt handler `dt282x_interrupt()` causes a null pointer dereference for those supported boards that have no analog output support. For these boards, `dev->write_subdev` will be `NULL` and therefore the `s_ao` subdevice pointer variable will be `NULL`. In that case, the following call near the end of the interrupt handler results in a null pointer dereference: comedi_handle_events(dev, s_ao); Fix it by only calling the above function if `s_ao` is valid. (There are other uses of `s_ao` by the interrupt handler that may or may not be reached depending on values of hardware registers. Trust that they are reliable for now.) Note: commit 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") propagates an earlier error from commit f21c74fa4cfe ("staging: comedi: dt282x: use cfc_handle_events()"). Fixes: 4f6f009b204f ("staging: comedi: dt282x: use comedi_handle_events()") Cc: # v3.19+ Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c index d5295bbdd28c..37133d54dda1 100644 --- a/drivers/staging/comedi/drivers/dt282x.c +++ b/drivers/staging/comedi/drivers/dt282x.c @@ -566,7 +566,8 @@ static irqreturn_t dt282x_interrupt(int irq, void *d) } #endif comedi_handle_events(dev, s); - comedi_handle_events(dev, s_ao); + if (s_ao) + comedi_handle_events(dev, s_ao); return IRQ_RETVAL(handled); }