comedi: pcm711: Fix sanity check in interrupt handler

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
commit f876cbfe3e