@@ -699,6 +699,10 @@ static int line6_init_cap_control(struct usb_line6 *line6)
line6->buffer_message = kmalloc(LINE6_MIDI_MESSAGE_MAXLEN, GFP_KERNEL);
if (!line6->buffer_message)
return -ENOMEM;
+
+ ret = line6_init_midi(line6);
+ if (ret < 0)
+ return ret;
} else {
ret = line6_hwdep_init(line6);
if (ret < 0)
@@ -376,11 +376,6 @@ static int pod_init(struct usb_line6 *line6,
if (err < 0)
return err;
- /* initialize MIDI subsystem: */
- err = line6_init_midi(line6);
- if (err < 0)
- return err;
-
/* initialize PCM subsystem: */
err = line6_init_pcm(line6, &pod_pcm_properties);
if (err < 0)
@@ -159,7 +159,6 @@ static int variax_init(struct usb_line6 *line6,
const struct usb_device_id *id)
{
struct usb_line6_variax *variax = line6_to_variax(line6);
- int err;
line6->process_message = line6_variax_process_message;
line6->disconnect = line6_variax_disconnect;
@@ -172,11 +171,6 @@ static int variax_init(struct usb_line6 *line6,
if (variax->buffer_activate == NULL)
return -ENOMEM;
- /* initialize MIDI subsystem: */
- err = line6_init_midi(&variax->line6);
- if (err < 0)
- return err;
-
/* initiate startup procedure: */
schedule_delayed_work(&line6->startup_work,
msecs_to_jiffies(VARIAX_STARTUP_DELAY1));
The initialization of MIDI devices that are found on some LINE6 drivers are currently done in a racy way; namely, the MIDI buffer instance is allocated and initialized in each private_init callback while the communication with the interface is already started via line6_init_cap_control() call before that point. This may lead to Oops in line6_data_received() when a spurious event is received, as reported by syzkaller. This patch moves the MIDI initialization to line6_init_cap_control() as well instead of the too-lately-called private_init for avoiding the race. Also this reduces slightly more lines, so it's a win-win change. Reported-by: syzbot+0d2b3feb0a2887862e06@syzkallerlkml..appspotmail.com Link: https://lore.kernel.org/r/000000000000a4be9405c28520de@google.com Link: https://lore.kernel.org/r/20210517132725.GA50495@hyeyoo Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: <stable@vger.kernel.org> Signed-off-by: Takashi Iwai <tiwai@suse.de> --- sound/usb/line6/driver.c | 4 ++++ sound/usb/line6/pod.c | 5 ----- sound/usb/line6/variax.c | 6 ------ 3 files changed, 4 insertions(+), 11 deletions(-)