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/cpuinfo.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 fs/proc/cpuinfo.c (limited to 'fs/proc/cpuinfo.c') diff --git a/fs/proc/cpuinfo.c b/fs/proc/cpuinfo.c new file mode 100644 index 000000000..f38bda5b8 --- /dev/null +++ b/fs/proc/cpuinfo.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +extern const struct seq_operations cpuinfo_op; + +static int cpuinfo_open(struct inode *inode, struct file *file) +{ + return seq_open(file, &cpuinfo_op); +} + +static const struct proc_ops cpuinfo_proc_ops = { + .proc_flags = PROC_ENTRY_PERMANENT, + .proc_open = cpuinfo_open, + .proc_read_iter = seq_read_iter, + .proc_lseek = seq_lseek, + .proc_release = seq_release, +}; + +static int __init proc_cpuinfo_init(void) +{ + proc_create("cpuinfo", 0, NULL, &cpuinfo_proc_ops); + return 0; +} +fs_initcall(proc_cpuinfo_init); -- cgit v1.3.1