From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock Add a sleepable verifier test that loads a graph-node local kptr in an explicit RCU read-side critical section, then passes its node to bpf_rbtree_remove() after the section ends. Before the verifier fix, the stale NON_OWN_REF flag makes the node look like a live borrowed reference and the program is accepted. After the fix, the pointer is demoted without NON_OWN_REF and the graph kfunc argument is rejected. Also exercise a graph kptr loaded while a spin lock provides implicit RCU protection. The pointer must be invalidated when the lock is released, which guards the required ordering between non-owning-reference invalidation and RCU demotion. Update the existing fault-protected load test state description. The post-unlock pointer no longer carries NON_OWN_REF, but remains readable because the load is rewritten to use BPF_PROBE_MEM. Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- fs/proc/loadavg.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) create mode 100644 fs/proc/loadavg.c (limited to 'fs/proc/loadavg.c') diff --git a/fs/proc/loadavg.c b/fs/proc/loadavg.c new file mode 100644 index 000000000..817981e57 --- /dev/null +++ b/fs/proc/loadavg.c @@ -0,0 +1,37 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +static int loadavg_proc_show(struct seq_file *m, void *v) +{ + unsigned long avnrun[3]; + + get_avenrun(avnrun, FIXED_1/200, 0); + + seq_printf(m, "%lu.%02lu %lu.%02lu %lu.%02lu %u/%d %d\n", + LOAD_INT(avnrun[0]), LOAD_FRAC(avnrun[0]), + LOAD_INT(avnrun[1]), LOAD_FRAC(avnrun[1]), + LOAD_INT(avnrun[2]), LOAD_FRAC(avnrun[2]), + nr_running(), nr_threads, + idr_get_cursor(&task_active_pid_ns(current)->idr) - 1); + return 0; +} + +static int __init proc_loadavg_init(void) +{ + struct proc_dir_entry *pde; + + pde = proc_create_single("loadavg", 0, NULL, loadavg_proc_show); + pde_make_permanent(pde); + return 0; +} +fs_initcall(proc_loadavg_init); -- cgit v1.3.1