Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

fuse: fix race between interrupt and resend

After commit f8fce75fedf7 ("fuse: clear intr_entry in fuse_resend and fuse_remove_pending_req") the WARN_ON(!list_empty(&req->intr_entry)) in fuse_request_free() still triggers due to the following race:

In request_wait_answer() if (test_bit(FR_SENT, &req->flags)) -> returns true

In fuse_chan_resend() clear_bit(FR_SENT, &req->flags)

In request_wait_answer() queue_interrupt(req)

Fix by:

- move clearing FR_SENT inside fpq->lock

- move setting FR_PENDING inside fiq->lock

- recheck FR_SENT after acquiring fiq->lock in fuse_dev_queue_interrupt()