In the Linux kernel, the following vulnerability has been resolved:
af_unix: Set gc_in_progress to true in unix_gc().
Igor Ushakov reported that unix_gc() could run with gc_in_progress
being false if the work is scheduled while running:
Thread 1 Thread 2 Thread 3
-------- -------- --------
unix_schedule_gc() unix_schedule_gc()
- if (!gc_in_progress)- if (!gc_in_progress)
|- gc_in_progress = true |
- queue_work() |
unix_gc() <----------------/ |
| |- gc_in_progress = true
...- queue_work()
| |
- gc_in_progress = false |
|
unix_gc() <---------------------------------------------'
|
... /* gc_in_progress == false */
|- gc_in_progress = false
unix_peek_fpl() relies on gc_in_progress not to confuse GC
by MSG_PEEK.
Let's set gc_in_progress to true in unix_gc().