6.12-stable review patch. If anyone has any objections, please let me know.
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From: Andrea Righi arighi@nvidia.com
commit 9360dfe4cbd62ff1eb8217b815964931523b75b3 upstream.
If a BPF scheduler provides an invalid CPU (outside the nr_cpu_ids range) as prev_cpu to scx_bpf_select_cpu_dfl() it can cause a kernel crash.
To prevent this, validate prev_cpu in scx_bpf_select_cpu_dfl() and trigger an scx error if an invalid CPU is specified.
Fixes: f0e1a0643a59b ("sched_ext: Implement BPF extensible scheduler class") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Andrea Righi arighi@nvidia.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/sched/ext.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6052,6 +6052,9 @@ __bpf_kfunc_start_defs(); __bpf_kfunc s32 scx_bpf_select_cpu_dfl(struct task_struct *p, s32 prev_cpu, u64 wake_flags, bool *is_idle) { + if (!ops_cpu_valid(prev_cpu, NULL)) + goto prev_cpu; + if (!static_branch_likely(&scx_builtin_idle_enabled)) { scx_ops_error("built-in idle tracking is disabled"); goto prev_cpu;