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ALSA: caiaq: Decoupling ep1_in_urb in caiaq dev

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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: 523f1dce37 ("[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 <eadavis@sina.com>
Link: https://patch.msgid.link/20260903130521.554840-1-eadavis@sina.com
Signed-off-by: Takashi Iwai <tiwai@suse.de>
This commit is contained in:
Edward Adam Davis 2026-09-03 21:05:21 +08:00 committed by Takashi Iwai
parent 3b26ceef88
commit 402a9d6aab
3 changed files with 29 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

36
sound/usb/caiaq/device.c
View File

@ -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);
}

4
sound/usb/caiaq/device.h
View File

@ -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;

6
sound/usb/caiaq/midi.c
View File

@ -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,"