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Message-Id: <20251007155808.438441-1-aha310510@gmail.com>
Date: Wed, 8 Oct 2025 00:58:08 +0900
From: Jeongjun Park <aha310510@...il.com>
To: stable@...r.kernel.org
Cc: Takashi Iwai <tiwai@...e.de>,
syzbot+d8f72178ab6783a7daea@...kaller.appspotmail.com,
Clemens Ladisch <clemens@...isch.de>,
Jaroslav Kysela <perex@...ex.cz>,
alsa-devel@...a-project.org,
linux-sound@...r.kernel.org,
linux-kernel@...r.kernel.org,
Jeongjun Park <aha310510@...il.com>
Subject: [PATCH 6.12.y 6.6.y 6.1.y 5.15.y 5.10.y 5.4.y] ALSA: usb-audio: Kill timer properly at removal
From: Takashi Iwai <tiwai@...e.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@...kaller.appspotmail.com
Closes: https://lore.kernel.org/681c70d7.050a0220.a19a9.00c6.GAE@google.com
Cc: <stable@...r.kernel.org>
Link: https://patch.msgid.link/20250519212031.14436-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@...e.de>
[ del_timer vs timer_delete differences ]
Signed-off-by: Jeongjun Park <aha310510@...il.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);
kfree(umidi);
}
@@ -1553,7 +1554,7 @@ void snd_usbmidi_disconnect(struct list_head *p)
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];
--
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