diff options
| author | Ian Abbott <abbotti@mev.co.uk> | 2026-02-25 13:24:27 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2026-04-11 14:29:51 +0200 |
| commit | 83134a7a176ce5b4b19b6edecf4360e8d98d1a5a (patch) | |
| tree | f1a49c7b7314928b22cc48b92a47d8e1c9ded235 /drivers | |
| parent | 830c848aba9f047eb6b34288975ebeb8e8621451 (diff) | |
comedi: Reinit dev->spinlock between attachments to low-level drivers
commit 4b9a9a6d71e3e252032f959fb3895a33acb5865c upstream.
`struct comedi_device` is the main controlling structure for a COMEDI
device created by the COMEDI subsystem. It contains a member `spinlock`
containing a spin-lock that is initialized by the COMEDI subsystem, but
is reserved for use by a low-level driver attached to the COMEDI device
(at least since commit 25436dc9d84f ("Staging: comedi: remove RT
code")).
Some COMEDI devices (those created on initialization of the COMEDI
subsystem when the "comedi.comedi_num_legacy_minors" parameter is
non-zero) can be attached to different low-level drivers over their
lifetime using the `COMEDI_DEVCONFIG` ioctl command. This can result in
inconsistent lock states being reported when there is a mismatch in the
spin-lock locking levels used by each low-level driver to which the
COMEDI device has been attached. Fix it by reinitializing
`dev->spinlock` before calling the low-level driver's `attach` function
pointer if `CONFIG_LOCKDEP` is enabled.
Reported-by: syzbot+cc9f7f4a7df09f53c4a4@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=cc9f7f4a7df09f53c4a4
Fixes: ed9eccbe8970 ("Staging: add comedi core")
Cc: stable <stable@kernel.org>
Signed-off-by: Ian Abbott <abbotti@mev.co.uk>
Link: https://patch.msgid.link/20260225132427.86578-1-abbotti@mev.co.uk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/comedi/drivers.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/drivers/comedi/drivers.c b/drivers/comedi/drivers.c index 69cd2a253c66..7453f778f2c3 100644 --- a/drivers/comedi/drivers.c +++ b/drivers/comedi/drivers.c @@ -1063,6 +1063,14 @@ int comedi_device_attach(struct comedi_device *dev, struct comedi_devconfig *it) ret = -EIO; goto out; } + if (IS_ENABLED(CONFIG_LOCKDEP)) { + /* + * dev->spinlock is for private use by the attached low-level + * driver. Reinitialize it to stop lock-dependency tracking + * between attachments to different low-level drivers. + */ + spin_lock_init(&dev->spinlock); + } dev->driver = driv; dev->board_name = dev->board_ptr ? *(const char **)dev->board_ptr : dev->driver->driver_name; |