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 --- scripts/kconfig/util.c | 121 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 121 insertions(+) create mode 100644 scripts/kconfig/util.c (limited to 'scripts/kconfig/util.c') diff --git a/scripts/kconfig/util.c b/scripts/kconfig/util.c new file mode 100644 index 000000000..0809aa061 --- /dev/null +++ b/scripts/kconfig/util.c @@ -0,0 +1,121 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright (C) 2002-2005 Roman Zippel + * Copyright (C) 2002-2005 Sam Ravnborg + */ + +#include +#include +#include + +#include +#include +#include +#include "lkc.h" + +/* hash table of all parsed Kconfig files */ +static HASHTABLE_DEFINE(file_hashtable, 1U << 11); + +struct file { + struct hlist_node node; + struct { + const char *name; + int lineno; + } parent; + char name[]; +}; + +static void die_duplicated_include(struct file *file, + const char *parent, int lineno) +{ + fprintf(stderr, + "%s:%d: error: repeated inclusion of %s\n" + "%s:%d: note: location of first inclusion of %s\n", + parent, lineno, file->name, + file->parent.name, file->parent.lineno, file->name); + exit(1); +} + +/* file already present in list? If not add it */ +const char *file_lookup(const char *name, + const char *parent_name, int parent_lineno) +{ + const char *parent = NULL; + struct file *file; + size_t len; + int hash = hash_str(name); + + if (parent_name) + parent = file_lookup(parent_name, NULL, 0); + + hash_for_each_possible(file_hashtable, file, node, hash) + if (!strcmp(name, file->name)) { + if (!parent_name) + return file->name; + die_duplicated_include(file, parent, parent_lineno); + } + + len = strlen(name); + file = xmalloc(sizeof(*file) + len + 1); + memset(file, 0, sizeof(*file)); + memcpy(file->name, name, len); + file->name[len] = '\0'; + file->parent.name = parent; + file->parent.lineno = parent_lineno; + + hash_add(file_hashtable, &file->node, hash); + + str_printf(&autoconf_cmd, "\t%s \\\n", name); + + return file->name; +} + +/* Allocate initial growable string */ +struct gstr str_new(void) +{ + struct gstr gs; + gs.s = xmalloc(sizeof(char) * 64); + gs.len = 64; + gs.max_width = 0; + strcpy(gs.s, "\0"); + return gs; +} + +/* Free storage for growable string */ +void str_free(struct gstr *gs) +{ + free(gs->s); + gs->s = NULL; + gs->len = 0; +} + +/* Append to growable string */ +void str_append(struct gstr *gs, const char *s) +{ + size_t l; + if (s) { + l = strlen(gs->s) + strlen(s) + 1; + if (l > gs->len) { + gs->s = xrealloc(gs->s, l); + gs->len = l; + } + strcat(gs->s, s); + } +} + +/* Append printf formatted string to growable string */ +void str_printf(struct gstr *gs, const char *fmt, ...) +{ + va_list ap; + char s[10000]; /* big enough... */ + va_start(ap, fmt); + vsnprintf(s, sizeof(s), fmt, ap); + str_append(gs, s); + va_end(ap); +} + +/* Retrieve value of growable string */ +char *str_get(const struct gstr *gs) +{ + return gs->s; +} -- cgit v1.3.1