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 --- tools/perf/tests/mem2node.c | 82 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 tools/perf/tests/mem2node.c (limited to 'tools/perf/tests/mem2node.c') diff --git a/tools/perf/tests/mem2node.c b/tools/perf/tests/mem2node.c new file mode 100644 index 000000000..7ce1ad7b6 --- /dev/null +++ b/tools/perf/tests/mem2node.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include +#include +#include "debug.h" +#include "env.h" +#include "mem2node.h" +#include "tests.h" + +static struct node { + int node; + const char *map; +} test_nodes[] = { + { .node = 0, .map = "0" }, + { .node = 1, .map = "1-2" }, + { .node = 3, .map = "5-7,9" }, +}; + +#define T TEST_ASSERT_VAL + +static unsigned long *get_bitmap(const char *str, int nbits) +{ + struct perf_cpu_map *map = perf_cpu_map__new(str); + unsigned long *bm = NULL; + + bm = bitmap_zalloc(nbits); + + if (map && bm) { + struct perf_cpu cpu; + unsigned int i; + + perf_cpu_map__for_each_cpu(cpu, i, map) + __set_bit(cpu.cpu, bm); + } + + if (map) + perf_cpu_map__put(map); + else + free(bm); + + return bm && map ? bm : NULL; +} + +static int test__mem2node(struct test_suite *t __maybe_unused, int subtest __maybe_unused) +{ + struct mem2node map; + struct memory_node nodes[3]; + struct perf_env env = { + .memory_nodes = (struct memory_node *) &nodes[0], + .nr_memory_nodes = ARRAY_SIZE(nodes), + .memory_bsize = 0x100, + }; + unsigned int i; + + for (i = 0; i < ARRAY_SIZE(nodes); i++) { + nodes[i].node = test_nodes[i].node; + nodes[i].size = 10; + + T("failed: alloc bitmap", + (nodes[i].set = get_bitmap(test_nodes[i].map, 10))); + } + + T("failed: mem2node__init", !mem2node__init(&map, &env)); + T("failed: mem2node__node", 0 == mem2node__node(&map, 0x50)); + T("failed: mem2node__node", 1 == mem2node__node(&map, 0x100)); + T("failed: mem2node__node", 1 == mem2node__node(&map, 0x250)); + T("failed: mem2node__node", 3 == mem2node__node(&map, 0x500)); + T("failed: mem2node__node", 3 == mem2node__node(&map, 0x650)); + T("failed: mem2node__node", -1 == mem2node__node(&map, 0x450)); + T("failed: mem2node__node", -1 == mem2node__node(&map, 0x1050)); + + for (i = 0; i < ARRAY_SIZE(nodes); i++) + zfree(&nodes[i].set); + + mem2node__exit(&map); + return 0; +} + +DEFINE_SUITE("mem2node", mem2node); -- cgit v1.3.1