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char: xillybus: Don't destroy workqueue from work item running on it

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Triggered by a kref decrement, destroy_workqueue() may be called from
within a work item for destroying its own workqueue. This illegal
situation is averted by adding a module-global workqueue for exclusive
use of the offending work item. Other work items continue to be queued
on per-device workqueues to ensure performance.

Reported-by: syzbot+91dbdfecdd3287734d8e@syzkaller.appspotmail.com
Cc: stable <stable@kernel.org>
Closes: https://lore.kernel.org/lkml/0000000000000ab25a061e1dfe9f@google.com/
Signed-off-by: Eli Billauer <eli.billauer@gmail.com>
Link: https://lore.kernel.org/r/20240801121126.60183-1-eli.billauer@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eli Billauer 2024-08-01 15:11:26 +03:00 committed by Greg Kroah-Hartman
parent 7c626ce4ba
commit ccbde4b128
1 changed files with 11 additions and 5 deletions
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16
drivers/char/xillybus/xillyusb.c
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@ -50,6 +50,7 @@ MODULE_LICENSE("GPL v2");
static const char xillyname[] = "xillyusb";
static unsigned int fifo_buf_order;
static struct workqueue_struct *wakeup_wq;
#define USB_VENDOR_ID_XILINX 0x03fd
#define USB_VENDOR_ID_ALTERA 0x09fb
@ -569,10 +570,6 @@ static void cleanup_dev(struct kref *kref)
* errors if executed. The mechanism relies on that xdev->error is assigned
* a non-zero value by report_io_error() prior to queueing wakeup_all(),
* which prevents bulk_in_work() from calling process_bulk_in().
*
* The fact that wakeup_all() and bulk_in_work() are queued on the same
* workqueue makes their concurrent execution very unlikely, however the
* kernel's API doesn't seem to ensure this strictly.
*/
static void wakeup_all(struct work_struct *work)
@ -627,7 +624,7 @@ static void report_io_error(struct xillyusb_dev *xdev,
if (do_once) {
kref_get(&xdev->kref); /* xdev is used by work item */
queue_work(xdev->workq, &xdev->wakeup_workitem);
queue_work(wakeup_wq, &xdev->wakeup_workitem);
}
}
@ -2258,6 +2255,10 @@ static int __init xillyusb_init(void)
{
int rc = 0;
wakeup_wq = alloc_workqueue(xillyname, 0, 0);
if (!wakeup_wq)
return -ENOMEM;
if (LOG2_INITIAL_FIFO_BUF_SIZE > PAGE_SHIFT)
fifo_buf_order = LOG2_INITIAL_FIFO_BUF_SIZE - PAGE_SHIFT;
else
@ -2265,11 +2266,16 @@ static int __init xillyusb_init(void)
rc = usb_register(&xillyusb_driver);
if (rc)
destroy_workqueue(wakeup_wq);
return rc;
}
static void __exit xillyusb_exit(void)
{
destroy_workqueue(wakeup_wq);
usb_deregister(&xillyusb_driver);
}