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()
