6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nguyen Ngoc Thang commit 0b7bd20f6379bc5e431fd74d866390f5b5b63f3c upstream. setup_card() registers the input device, whose name and phys point into struct snd_usb_caiaqdev, and then goes on to snd_card_register() and snd_usb_caiaq_control_init(). If either fails, snd_probe() calls snd_card_free(), which frees the device state but leaves the input device registered: card_free() only clears the pointer, and the input device is unregistered from snd_disconnect() alone. Reading its "uevent" attribute afterwards dereferences freed memory: BUG: KASAN: slab-use-after-free in string+0x4a9/0x4f0 Read of size 1 at addr ffff8880208f5043 by task caiaq/4967 add_uevent_var+0x183/0x3a0 input_dev_uevent+0x162/0x900 dev_uevent+0x2f1/0x870 uevent_show+0x1ca/0x3a0 ... Unregister the input device on the probe error path, as snd_disconnect() does. snd_usb_caiaq_input_disconnect() is a no-op when no input device was registered. Reproduced with a raw-gadget Audio Kontrol 1 and a temporary hack that makes snd_usb_caiaq_control_init() fail. Fixes: 28abd224db4a ("ALSA: caiaq: Handle probe errors properly") Cc: stable@vger.kernel.org Reported-by: syzbot+2a123f6269da57ffefaa@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=2a123f6269da57ffefaa Signed-off-by: Nguyen Ngoc Thang Link: https://patch.msgid.link/20260925170717.22462-1-ngocthang2710.1999@gmail.com Signed-off-by: Takashi Iwai Signed-off-by: Greg Kroah-Hartman --- sound/usb/caiaq/device.c | 3 +++ 1 file changed, 3 insertions(+) --- a/sound/usb/caiaq/device.c +++ b/sound/usb/caiaq/device.c @@ -562,6 +562,9 @@ static int snd_probe(struct usb_interfac ret = init_card(caiaqdev(card)); if (ret < 0) { dev_err(&usb_dev->dev, "unable to init card! (ret=%d)\n", ret); +#ifdef CONFIG_SND_USB_CAIAQ_INPUT + snd_usb_caiaq_input_disconnect(caiaqdev(card)); +#endif snd_card_free(card); return ret; }