linux-kernel - Re: [syzbot] [sound?] [usb?] general protection fault in snd_usbmidi_do

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Message-ID: <87ms6g9kn1.wl-tiwai@suse.de>
Date: Sat, 27 Sep 2025 13:53:38 +0200
From: Takashi Iwai <tiwai@...e.de>
To: syzbot <syzbot+f02665daa2abeef4a947@...kaller.appspotmail.com>
Cc: aha310510@...il.com,
	clemens@...isch.de,
	hdanton@...a.com,
	linux-kernel@...r.kernel.org,
	linux-sound@...r.kernel.org,
	perex@...ex.cz,
	syzkaller-bugs@...glegroups.com,
	tiwai@...e.de
Subject: Re: [syzbot] [sound?] [usb?] general protection fault in snd_usbmidi_do_output

On Sat, 27 Sep 2025 12:55:01 +0200,
syzbot wrote:
> 
> Hello,
> 
> syzbot has tested the proposed patch but the reproducer is still triggering an issue:
> KASAN: slab-use-after-free Read in snd_usbmidi_in_urb_complete

Another try.

#syz test upstream master

--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -1522,6 +1522,9 @@ static void snd_usbmidi_free(struct snd_usb_midi *umidi)
 {
 	int i;
 
+	if (!umidi->disconnected)
+		snd_usbmidi_disconnect(&umidi->list);
+
 	for (i = 0; i < MIDI_MAX_ENDPOINTS; ++i) {
 		struct snd_usb_midi_endpoint *ep = &umidi->endpoints[i];
 		if (ep->out)