From b8336be66dec06bef518030a0df9847122053ec5 Mon Sep 17 00:00:00 2001
From: Ian Abbott <abbotti@mev.co.uk>
Date: Wed, 26 Jun 2019 14:18:04 +0100
Subject: [PATCH] staging: comedi: dt282x: fix a null pointer deref on interrupt
Git-commit: b8336be66dec06bef518030a0df9847122053ec5
Patch-mainline: v5.3-rc1
References: bsc#1051510
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: <stable@vger.kernel.org> # v3.19+
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/staging/comedi/drivers/dt282x.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/staging/comedi/drivers/dt282x.c b/drivers/staging/comedi/drivers/dt282x.c
index 3be927f1d3a9..e15e33ed94ae 100644
--- a/drivers/staging/comedi/drivers/dt282x.c
+++ b/drivers/staging/comedi/drivers/dt282x.c
@@ -557,7 +557,8 @@ 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);
}
--
2.16.4