6.6-stable review patch. If anyone has any objections, please let me know.
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From: Takashi Iwai tiwai@suse.de
commit 0718a78f6a9f04b88d0dc9616cc216b31c5f3cf1 upstream.
The USB-audio MIDI code initializes the timer, but in a rare case, the driver might be freed without the disconnect call. This leaves the timer in an active state while the assigned object is released via snd_usbmidi_free(), which ends up with a kernel warning when the debug configuration is enabled, as spotted by fuzzer.
For avoiding the problem, put timer_shutdown_sync() at snd_usbmidi_free(), so that the timer can be killed properly. While we're at it, replace the existing timer_delete_sync() at the disconnect callback with timer_shutdown_sync(), too.
Reported-by: syzbot+d8f72178ab6783a7daea@syzkaller.appspotmail.com Closes: https://lore.kernel.org/681c70d7.050a0220.a19a9.00c6.GAE@google.com Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20250519212031.14436-1-tiwai@suse.de Signed-off-by: Takashi Iwai tiwai@suse.de [ del_timer vs timer_delete differences ] Signed-off-by: Jeongjun Park aha310510@gmail.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- sound/usb/midi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1530,6 +1530,7 @@ static void snd_usbmidi_free(struct snd_ snd_usbmidi_in_endpoint_delete(ep->in); } mutex_destroy(&umidi->mutex); + timer_shutdown_sync(&umidi->error_timer); kfree(umidi); }
@@ -1553,7 +1554,7 @@ void snd_usbmidi_disconnect(struct list_ spin_unlock_irq(&umidi->disc_lock); up_write(&umidi->disc_rwsem);
- del_timer_sync(&umidi->error_timer); + timer_shutdown_sync(&umidi->error_timer);
for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) { struct snd_usb_midi_endpoint *ep = &umidi->endpoints[i];