From 95f76f51937fdfb0fc1e14cae606b1ef574a56f3 Mon Sep 17 00:00:00 2001 From: Diego Fernando Mancera Gomez Date: Thu, 23 Jul 2026 12:22:42 -0600 Subject: [PATCH] media: em28xx: defer audio-only extension registration The audio-only path registers extensions while probing the primary device. For a dual-TS board, this happens before dev_next is created. The duplicate device inherits is_audio_only and is then independently inserted into em28xx_devlist. The list is intended to contain only primary devices: extension operations reach the secondary device through dev_next. The independently linked secondary can be freed during disconnect while its list node remains reachable, resulting in a use-after-free. Defer audio-only extension registration to the module-request work item. It runs only after probing has completed construction of the optional secondary device, so only the primary is registered and extension callbacks reach the secondary through dev_next. Fixes: 4a089668ef22 ("media: em28xx-cards: rework the em28xx probing code") Cc: stable@vger.kernel.org Reported-by: syzbot+a11c46f37ee083a73deb@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/66ec3c83.050a0220.29194.002f.GAE@google.com/T/ Suggested-by: Fedor Pchelkin Signed-off-by: Diego Fernando Mancera Gomez Signed-off-by: Hans Verkuil --- drivers/media/usb/em28xx/em28xx-cards.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/media/usb/em28xx/em28xx-cards.c b/drivers/media/usb/em28xx/em28xx-cards.c index b94b00456bcd..b7c534fc8a21 100644 --- a/drivers/media/usb/em28xx/em28xx-cards.c +++ b/drivers/media/usb/em28xx/em28xx-cards.c @@ -3675,6 +3675,7 @@ static void request_module_async(struct work_struct *work) * intf. Don't register extensions twice on those devices. */ if (dev->is_audio_only) { + em28xx_init_extension(dev); #if defined(CONFIG_MODULES) && defined(MODULE) request_module("em28xx-alsa"); #endif @@ -3913,8 +3914,6 @@ static int em28xx_init_dev(struct em28xx *dev, struct usb_device *udev, retval = -ENODEV; goto err_deinit_media; } - em28xx_init_extension(dev); - return 0; }