In the Linux kernel, the following vulnerability has been resolved: fuse: fix race between interrupt and resend After commit f8fce75fedf7

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()