Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Don't run ops.dequeue() with a DSQ lock held ops.dequeue() is invoked with the source user DSQ's lock still held on the consume and move paths (scx_consume_dispatch_q(), move_task_between_dsqs()). A BPF scheduler which locks the source user DSQ from ops.dequeue() - e.g. by iterating it with bpf_iter_scx_dsq - self-deadlocks. ops.dequeue() can only call the "any" kfuncs and none of them can lock a builtin DSQ, so the global and bypass paths can't deadlock; however, all DSQ locks share one lockdep class, so iterating any user DSQ from ops.dequeue() on those paths trips the recursion check. Move the invocation after the DSQ unlock on all three paths. SCX_TASK_IN_CUSTODY is cleared under the lock serializing the transfer so that the callback is invoked exactly once.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d before fe499ae9da46e297f578d4346c4c8e338c3118db; affected ebf1ccff79c43f860cbd2f9d6cfab9a462d0cb2d before cb86607ada73185f321baa7f9d94a08a3a40bbf5 |
| Linux / Linux | affected 7.1; unaffected 0 before 7.1; unaffected 7.2.10 through 7.2.*; unaffected 7.3 through * |
CWE
No CWE identifiers supplied.