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comedi: pcm711: Fix sanity check in interrupt handler

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The driver requests an interrupt handler for the device before it is
fully set up.

For safety, the interrupt handler checks the dev->attached flag to
ensure the device is fully set up, but it currently does that after
dereferencing the dev->read_dev pointer which may be NULL if
dev->attached is false.  Move the check to avoid the possible null
pointer dereference.

Reported-by: Jaeyoung Chung <jjy600901@snu.ac.kr>
Link: https://lore.kernel.org/lkml/20260610115912.780131-1-jjy600901@snu.ac.kr/
Reported-by: Sangyun Kim <sangyun.kim@snu.ac.kr>
Reported-by: Kyungwook Boo <bookyungwook@gmail.com>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260618102949.26607-7-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ian Abbott 2026-06-18 11:09:13 +01:00 committed by Greg Kroah-Hartman
parent 13f4796223
commit f876cbfe3e
1 changed files with 2 additions and 1 deletions
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3
drivers/comedi/drivers/pcl711.c
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@ -184,7 +184,7 @@ static irqreturn_t pcl711_interrupt(int irq, void *d)
{
struct comedi_device *dev = d;
struct comedi_subdevice *s = dev->read_subdev;
struct comedi_cmd *cmd = &s->async->cmd;
struct comedi_cmd *cmd;
unsigned short data;
if (!dev->attached) {
@ -192,6 +192,7 @@ static irqreturn_t pcl711_interrupt(int irq, void *d)
return IRQ_HANDLED;
}
cmd = &s->async->cmd;
data = pcl711_ai_get_sample(dev, s);
outb(PCL711_INT_STAT_CLR, dev->iobase + PCL711_INT_STAT_REG);