Patch "ALSA: 6fire: Release resources at card release" has been added to the 5.4-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    ALSA: 6fire: Release resources at card release

to the 5.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-6fire-release-resources-at-card-release.patch
and it can be found in the queue-5.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 081b5a04e02e0a353ff1d24df48427d15f524fb9
Author: Takashi Iwai <tiwai@xxxxxxx>
Date:   Wed Nov 13 12:10:39 2024 +0100

    ALSA: 6fire: Release resources at card release
    
    [ Upstream commit a0810c3d6dd2d29a9b92604d682eacd2902ce947 ]
    
    The current 6fire code tries to release the resources right after the
    call of usb6fire_chip_abort().  But at this moment, the card object
    might be still in use (as we're calling snd_card_free_when_closed()).
    
    For avoid potential UAFs, move the release of resources to the card's
    private_free instead of the manual call of usb6fire_chip_destroy() at
    the USB disconnect callback.
    
    Fixes: c6d43ba816d1 ("ALSA: usb/6fire - Driver for TerraTec DMX 6Fire USB")
    Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
    Link: https://patch.msgid.link/20241113111042.15058-6-tiwai@xxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/sound/usb/6fire/chip.c b/sound/usb/6fire/chip.c
index 08c6e6a52eb98..ad6f89845a5c2 100644
--- a/sound/usb/6fire/chip.c
+++ b/sound/usb/6fire/chip.c
@@ -62,8 +62,10 @@ static void usb6fire_chip_abort(struct sfire_chip *chip)
 	}
 }
 
-static void usb6fire_chip_destroy(struct sfire_chip *chip)
+static void usb6fire_card_free(struct snd_card *card)
 {
+	struct sfire_chip *chip = card->private_data;
+
 	if (chip) {
 		if (chip->pcm)
 			usb6fire_pcm_destroy(chip);
@@ -73,8 +75,6 @@ static void usb6fire_chip_destroy(struct sfire_chip *chip)
 			usb6fire_comm_destroy(chip);
 		if (chip->control)
 			usb6fire_control_destroy(chip);
-		if (chip->card)
-			snd_card_free(chip->card);
 	}
 }
 
@@ -137,6 +137,7 @@ static int usb6fire_chip_probe(struct usb_interface *intf,
 	chip->regidx = regidx;
 	chip->intf_count = 1;
 	chip->card = card;
+	card->private_free = usb6fire_card_free;
 
 	ret = usb6fire_comm_init(chip);
 	if (ret < 0)
@@ -163,7 +164,7 @@ static int usb6fire_chip_probe(struct usb_interface *intf,
 	return 0;
 
 destroy_chip:
-	usb6fire_chip_destroy(chip);
+	snd_card_free(card);
 	return ret;
 }
 
@@ -182,7 +183,6 @@ static void usb6fire_chip_disconnect(struct usb_interface *intf)
 
 			chip->shutdown = true;
 			usb6fire_chip_abort(chip);
-			usb6fire_chip_destroy(chip);
 		}
 	}
 }