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/overlayfs/params.h | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 fs/overlayfs/params.h (limited to 'fs/overlayfs/params.h') diff --git a/fs/overlayfs/params.h b/fs/overlayfs/params.h new file mode 100644 index 000000000..ffd53cdd8 --- /dev/null +++ b/fs/overlayfs/params.h @@ -0,0 +1,44 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ + +#include +#include + +struct ovl_fs; +struct ovl_config; + +extern const struct fs_parameter_spec ovl_parameter_spec[]; +extern const struct constant_table ovl_parameter_redirect_dir[]; + +/* The set of options that user requested explicitly via mount options */ +struct ovl_opt_set { + bool metacopy; + bool redirect; + bool nfs_export; + bool index; +}; + +#define OVL_MAX_STACK 500 + +struct ovl_fs_context_layer { + char *name; + struct path path; +}; + +struct ovl_fs_context { + struct path upper; + struct path work; + size_t capacity; + size_t nr; /* includes nr_data */ + size_t nr_data; + struct ovl_opt_set set; + struct ovl_fs_context_layer *lower; + char *lowerdir_all; /* user provided lowerdir string */ + bool casefold_set; +}; + +int ovl_init_fs_context(struct fs_context *fc); +void ovl_free_fs(struct ovl_fs *ofs); +int ovl_fs_params_verify(const struct ovl_fs_context *ctx, + struct ovl_config *config); +int ovl_show_options(struct seq_file *m, struct dentry *dentry); +const char *ovl_xino_mode(struct ovl_config *config); -- cgit v1.3.1