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/coda/sysctl.c | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 fs/coda/sysctl.c (limited to 'fs/coda/sysctl.c') diff --git a/fs/coda/sysctl.c b/fs/coda/sysctl.c new file mode 100644 index 000000000..0df46f09b --- /dev/null +++ b/fs/coda/sysctl.c @@ -0,0 +1,53 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Sysctl operations for Coda filesystem + * Original version: (C) 1996 P. Braam and M. Callahan + * Rewritten for Linux 2.1. (C) 1997 Carnegie Mellon University + * + * Carnegie Mellon encourages users to contribute improvements to + * the Coda project. Contact Peter Braam (coda@cs.cmu.edu). + */ + +#include + +#include "coda_int.h" + +static struct ctl_table_header *fs_table_header; + +static const struct ctl_table coda_table[] = { + { + .procname = "timeout", + .data = &coda_timeout, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "hard", + .data = &coda_hard, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec + }, + { + .procname = "fake_statfs", + .data = &coda_fake_statfs, + .maxlen = sizeof(int), + .mode = 0600, + .proc_handler = proc_dointvec + }, +}; + +void coda_sysctl_init(void) +{ + if ( !fs_table_header ) + fs_table_header = register_sysctl("coda", coda_table); +} + +void coda_sysctl_clean(void) +{ + if ( fs_table_header ) { + unregister_sysctl_table(fs_table_header); + fs_table_header = NULL; + } +} -- cgit v1.3.1