From 402a9d6aab7ac787ab075adeb562c3db8b8f564b Mon Sep 17 00:00:00 2001 From: Edward Adam Davis Date: Thu, 3 Sep 2026 21:05:21 +0800 Subject: [PATCH] ALSA: caiaq: Decoupling ep1_in_urb in caiaq dev The epq_in_urb object belonging to the caiaq device is coupled within the struct snd_usb_caiaqdev. After usb_submit_urb(epq_in_urb, GFP_KERNEL) executes successfully, epq_in_urb is successfully added to the urbp_list queue of the dummy HCD driver (userspace specifies dummy_hcd as the HCD layer driver for the caiaq USB device). When init_card() calls snd_usb_caiaq_send_command() which subsequently fails due to a timeout, and proceeds to call snd_card_free() to release the card, the embedded ep1_in_urb object is also freed. When the dummy HCD driver detects that the URB has been unlinked, it returns the URB (by usb_hcd_giveback_urb()), which triggers [1]. Decouple the ep1_in_urb object from the struct snd_usb_caiaqdev and switch to using a pointer instead. Separately allocate and manage the memory for ep1_in_urb to prevent the release of the snd_card memory object from interfering with it. midi_out_urb has the same issue as ep1_in_urb and is handled in the same way. [1] BUG: KASAN: slab-use-after-free in usb_free_urb+0x24/0x120 drivers/usb/core/urb.c:96 Write of size 4 at addr ffff88803cee1050 by task ktimers/1/29 Call Trace: usb_free_urb+0x24/0x120 drivers/usb/core/urb.c:96 dummy_timer+0xaac/0x4d50 drivers/usb/gadget/udc/dummy_hcd.c:2019 __run_hrtimer kernel/time/hrtimer.c:2067 [inline] __hrtimer_run_queues+0x3eb/0xaf0 kernel/time/hrtimer.c:2124 hrtimer_run_softirq+0x1e1/0x2e0 kernel/time/hrtimer.c:2141 Allocated by task 36: snd_card_new+0x7b/0x110 sound/core/init.c:184 create_card sound/usb/caiaq/device.c:429 [inline] snd_probe+0x236/0x1af0 sound/usb/caiaq/device.c:544 Freed by task 36: snd_card_free_when_closed sound/core/init.c:630 [inline] snd_card_free+0x138/0x1d0 sound/core/init.c:662 snd_probe+0x162b/0x1af0 sound/usb/caiaq/device.c:553 Fixes: 523f1dce3743 ("[ALSA] Add Native Instrument usb audio device support") Reported-by: syzbot+832ce9fa3face1b7d44d@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=832ce9fa3face1b7d44d Tested-by: syzbot+832ce9fa3face1b7d44d@syzkaller.appspotmail.com Signed-off-by: Edward Adam Davis Link: https://patch.msgid.link/20260903130521.554840-1-eadavis@sina.com Signed-off-by: Takashi Iwai --- sound/usb/caiaq/device.c | 36 ++++++++++++++++++++++++------------ sound/usb/caiaq/device.h | 4 ++-- sound/usb/caiaq/midi.c | 6 +++--- 3 files changed, 29 insertions(+), 17 deletions(-) diff --git a/sound/usb/caiaq/device.c b/sound/usb/caiaq/device.c index a16e59248480..3d821fde4582 100644 --- a/sound/usb/caiaq/device.c +++ b/sound/usb/caiaq/device.c @@ -192,8 +192,8 @@ static void usb_ep1_command_reply_dispatch (struct urb* urb) break; } - cdev->ep1_in_urb.actual_length = 0; - ret = usb_submit_urb(&cdev->ep1_in_urb, GFP_ATOMIC); + cdev->ep1_in_urb->actual_length = 0; + ret = usb_submit_urb(cdev->ep1_in_urb, GFP_ATOMIC); if (ret < 0) dev_err(dev, "unable to submit urb. OOM!?\n"); } @@ -408,6 +408,10 @@ static void card_free(struct snd_card *card) #endif snd_usb_caiaq_audio_free(cdev); usb_put_dev(cdev->chip.dev); + usb_free_urb(cdev->ep1_in_urb); + cdev->ep1_in_urb = NULL; + usb_free_urb(cdev->midi_out_urb); + cdev->midi_out_urb = NULL; } static int create_card(struct usb_device *usb_dev, @@ -457,22 +461,30 @@ static int init_card(struct snd_usb_caiaqdev *cdev) return -EIO; } - usb_init_urb(&cdev->ep1_in_urb); - usb_init_urb(&cdev->midi_out_urb); + cdev->ep1_in_urb = usb_alloc_urb(0, GFP_KERNEL); + if (!cdev->ep1_in_urb) + return -ENOMEM; - usb_fill_bulk_urb(&cdev->ep1_in_urb, usb_dev, + cdev->midi_out_urb = usb_alloc_urb(0, GFP_KERNEL); + if (!cdev->midi_out_urb) { + usb_free_urb(cdev->ep1_in_urb); + cdev->ep1_in_urb = NULL; + return -ENOMEM; + } + + usb_fill_bulk_urb(cdev->ep1_in_urb, usb_dev, usb_rcvbulkpipe(usb_dev, 0x1), cdev->ep1_in_buf, EP1_BUFSIZE, usb_ep1_command_reply_dispatch, cdev); - usb_fill_bulk_urb(&cdev->midi_out_urb, usb_dev, + usb_fill_bulk_urb(cdev->midi_out_urb, usb_dev, usb_sndbulkpipe(usb_dev, 0x1), cdev->midi_out_buf, EP1_BUFSIZE, snd_usb_caiaq_midi_output_done, cdev); /* sanity checks of EPs before actually submitting */ - if (usb_urb_ep_type_check(&cdev->ep1_in_urb) || - usb_urb_ep_type_check(&cdev->midi_out_urb)) { + if (usb_urb_ep_type_check(cdev->ep1_in_urb) || + usb_urb_ep_type_check(cdev->midi_out_urb)) { dev_err(dev, "invalid EPs\n"); return -EINVAL; } @@ -480,7 +492,7 @@ static int init_card(struct snd_usb_caiaqdev *cdev) init_waitqueue_head(&cdev->ep1_wait_queue); init_waitqueue_head(&cdev->prepare_wait_queue); - if (usb_submit_urb(&cdev->ep1_in_urb, GFP_KERNEL) != 0) + if (usb_submit_urb(cdev->ep1_in_urb, GFP_KERNEL) != 0) return -EIO; err = snd_usb_caiaq_send_command(cdev, EP1_CMD_GET_DEVICE_INFO, NULL, 0); @@ -530,7 +542,7 @@ static int init_card(struct snd_usb_caiaqdev *cdev) return 0; err_kill_urb: - usb_kill_urb(&cdev->ep1_in_urb); + usb_kill_urb(cdev->ep1_in_urb); return err; } @@ -576,8 +588,8 @@ static void snd_disconnect(struct usb_interface *intf) #endif snd_usb_caiaq_audio_disconnect(cdev); - usb_kill_urb(&cdev->ep1_in_urb); - usb_kill_urb(&cdev->midi_out_urb); + usb_kill_urb(cdev->ep1_in_urb); + usb_kill_urb(cdev->midi_out_urb); snd_card_free_when_closed(card); } diff --git a/sound/usb/caiaq/device.h b/sound/usb/caiaq/device.h index 743eb0387b5f..1c6f34693fa8 100644 --- a/sound/usb/caiaq/device.h +++ b/sound/usb/caiaq/device.h @@ -60,8 +60,8 @@ struct snd_usb_caiaq_cb_info; struct snd_usb_caiaqdev { struct snd_usb_audio chip; - struct urb ep1_in_urb; - struct urb midi_out_urb; + struct urb *ep1_in_urb; + struct urb *midi_out_urb; struct urb **data_urbs_in; struct urb **data_urbs_out; struct snd_usb_caiaq_cb_info *data_cb_info; diff --git a/sound/usb/caiaq/midi.c b/sound/usb/caiaq/midi.c index c656d0162432..18529484c8dc 100644 --- a/sound/usb/caiaq/midi.c +++ b/sound/usb/caiaq/midi.c @@ -43,7 +43,7 @@ static int snd_usb_caiaq_midi_output_close(struct snd_rawmidi_substream *substre { struct snd_usb_caiaqdev *cdev = substream->rmidi->private_data; if (cdev->midi_out_active) { - usb_kill_urb(&cdev->midi_out_urb); + usb_kill_urb(cdev->midi_out_urb); cdev->midi_out_active = 0; } return 0; @@ -64,9 +64,9 @@ static void snd_usb_caiaq_midi_send(struct snd_usb_caiaqdev *cdev, return; cdev->midi_out_buf[2] = len; - cdev->midi_out_urb.transfer_buffer_length = len+3; + cdev->midi_out_urb->transfer_buffer_length = len+3; - ret = usb_submit_urb(&cdev->midi_out_urb, GFP_ATOMIC); + ret = usb_submit_urb(cdev->midi_out_urb, GFP_ATOMIC); if (ret < 0) dev_err(dev, "snd_usb_caiaq_midi_send(%p): usb_submit_urb() failed,"