[PATCH next 2/2] sound: usb: fix use after free in usb_audio_disconnect

From: Pavel Skripkin <paskripkin@gmail.com>
To: perex@perex.cz, tiwai@suse.com, kai.heng.feng@canonical.com
Cc: alsa-devel@alsa-project.org, linux-kernel@vger.kernel.org,
	Pavel Skripkin <paskripkin@gmail.com>
Subject: [PATCH next 2/2] sound: usb: fix use after free in usb_audio_disconnect
Date: Tue,  9 Mar 2021 01:30:57 +0300	[thread overview]
Message-ID: <16da19126ff461e5e64a9aec648cce28fb8ed73e.1615242183.git.paskripkin@gmail.com> (raw)
In-Reply-To: <cover.1615242183.git.paskripkin@gmail.com>

The problem was in wrong "if" placement. chip->quirk_type is freed
in snd_card_free_when_closed(), but inside if statement it's accesed.

Fixes: 9799110825db ("ALSA: usb-audio: Disable USB autosuspend properly in setup_disable_autosuspend()"
Signed-off-by: Pavel Skripkin <paskripkin@gmail.com>
---
 sound/usb/card.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/sound/usb/card.c b/sound/usb/card.c
index 3fd1743513b5..b6f4c0848e66 100644
--- a/sound/usb/card.c
+++ b/sound/usb/card.c
@@ -907,6 +907,9 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 		}
 	}
 
+	if (chip->quirk_type & QUIRK_SETUP_DISABLE_AUTOSUSPEND)
+		usb_enable_autosuspend(interface_to_usbdev(intf));
+
 	chip->num_interfaces--;
 	if (chip->num_interfaces <= 0) {
 		usb_chip[chip->index] = NULL;
@@ -915,9 +918,6 @@ static void usb_audio_disconnect(struct usb_interface *intf)
 	} else {
 		mutex_unlock(&register_mutex);
 	}
-
-	if (chip->quirk_type & QUIRK_SETUP_DISABLE_AUTOSUSPEND)
-		usb_enable_autosuspend(interface_to_usbdev(intf));
 }
 
 /* lock the shutdown (disconnect) task and autoresume */
-- 
2.25.1

