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/devices.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 64 insertions(+) create mode 100644 fs/proc/devices.c (limited to 'fs/proc/devices.c') diff --git a/fs/proc/devices.c b/fs/proc/devices.c new file mode 100644 index 000000000..fe7bfcb7d --- /dev/null +++ b/fs/proc/devices.c @@ -0,0 +1,64 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include "internal.h" + +static int devinfo_show(struct seq_file *f, void *v) +{ + int i = *(loff_t *) v; + + if (i < CHRDEV_MAJOR_MAX) { + if (i == 0) + seq_puts(f, "Character devices:\n"); + chrdev_show(f, i); + } +#ifdef CONFIG_BLOCK + else { + i -= CHRDEV_MAJOR_MAX; + if (i == 0) + seq_puts(f, "\nBlock devices:\n"); + blkdev_show(f, i); + } +#endif + return 0; +} + +static void *devinfo_start(struct seq_file *f, loff_t *pos) +{ + if (*pos < (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) + return pos; + return NULL; +} + +static void *devinfo_next(struct seq_file *f, void *v, loff_t *pos) +{ + (*pos)++; + if (*pos >= (BLKDEV_MAJOR_MAX + CHRDEV_MAJOR_MAX)) + return NULL; + return pos; +} + +static void devinfo_stop(struct seq_file *f, void *v) +{ + /* Nothing to do */ +} + +static const struct seq_operations devinfo_ops = { + .start = devinfo_start, + .next = devinfo_next, + .stop = devinfo_stop, + .show = devinfo_show +}; + +static int __init proc_devices_init(void) +{ + struct proc_dir_entry *pde; + + pde = proc_create_seq("devices", 0, NULL, &devinfo_ops); + pde_make_permanent(pde); + return 0; +} +fs_initcall(proc_devices_init); -- cgit v1.3.1