The patch below does not apply to the 6.13-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.13.y git checkout FETCH_HEAD git cherry-pick -x 9360dfe4cbd62ff1eb8217b815964931523b75b3 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025031611-flatly-revolving-8c7b@gregkh' --subject-prefix 'PATCH 6.13.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 9360dfe4cbd62ff1eb8217b815964931523b75b3 Mon Sep 17 00:00:00 2001 From: Andrea Righi arighi@nvidia.com Date: Mon, 3 Mar 2025 18:51:59 +0100 Subject: [PATCH] sched_ext: Validate prev_cpu in scx_bpf_select_cpu_dfl()

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

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c index 0f1da199cfc7..7b9dfee858e7 100644 --- a/kernel/sched/ext.c +++ b/kernel/sched/ext.c @@ -6422,6 +6422,9 @@ static bool check_builtin_idle_enabled(void) __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 (!check_builtin_idle_enabled()) goto prev_cpu;