diff options
| author | Tejun Heo <tj@kernel.org> | 2026-04-24 14:31:35 -1000 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2026-04-24 14:31:35 -1000 |
| commit | 4fda9f0e7c950da4fe03cedeb2ac818edf5d03e9 (patch) | |
| tree | cd1b6adff1970c12664671392d422a61712383b5 | |
| parent | 411d3ef1a70589755e3beed2f5bf1f8aa0c27d1a (diff) | |
sched_ext: Guard scx_dsq_move() against NULL kit->dsq after failed iter_new
bpf_iter_scx_dsq_new() clears kit->dsq on failure and
bpf_iter_scx_dsq_{next,destroy}() guard against that. scx_dsq_move() doesn't -
it dereferences kit->dsq immediately, so a BPF program that calls
scx_bpf_dsq_move[_vtime]() after a failed iter_new oopses the kernel.
Return false if kit->dsq is NULL.
Fixes: 4c30f5ce4f7a ("sched_ext: Implement scx_bpf_dispatch[_vtime]_from_dsq()")
Cc: stable@vger.kernel.org # v6.12+
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
| -rw-r--r-- | kernel/sched/ext.c | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 7f991ecb1398..68c67113204f 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -8076,12 +8076,22 @@ static bool scx_dsq_move(struct bpf_iter_scx_dsq_kern *kit, struct task_struct *p, u64 dsq_id, u64 enq_flags) { struct scx_dispatch_q *src_dsq = kit->dsq, *dst_dsq; - struct scx_sched *sch = src_dsq->sched; + struct scx_sched *sch; struct rq *this_rq, *src_rq, *locked_rq; bool dispatched = false; bool in_balance; unsigned long flags; + /* + * The verifier considers an iterator slot initialized on any + * KF_ITER_NEW return, so a BPF program may legally reach here after + * bpf_iter_scx_dsq_new() failed and left @kit->dsq NULL. + */ + if (unlikely(!src_dsq)) + return false; + + sch = src_dsq->sched; + if (!scx_vet_enq_flags(sch, dsq_id, &enq_flags)) return false; |