On Wed, Oct 08, 2025 at 12:58:08AM +0900, Jeongjun Park wrote:
From: Takashi Iwai tiwai@suse.de
[ Upstream commit 0718a78f6a9f04b88d0dc9616cc216b31c5f3cf1 ]
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
sound/usb/midi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sound/usb/midi.c b/sound/usb/midi.c index a792ada18863..c3de2b137435 100644 --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1530,6 +1530,7 @@ static void snd_usbmidi_free(struct snd_usb_midi *umidi) snd_usbmidi_in_endpoint_delete(ep->in); } mutex_destroy(&umidi->mutex);
- timer_shutdown_sync(&umidi->error_timer);
This function is not in older kernel versions, you did not test this build :(
I've applied this to 6.6.y and newer, but for 6.1.y and older, please use the proper function.
thanks,
greg k-h