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 --- drivers/base/regmap/regmap-ram.c | 91 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 drivers/base/regmap/regmap-ram.c (limited to 'drivers/base/regmap/regmap-ram.c') diff --git a/drivers/base/regmap/regmap-ram.c b/drivers/base/regmap/regmap-ram.c new file mode 100644 index 000000000..c7356b0d8 --- /dev/null +++ b/drivers/base/regmap/regmap-ram.c @@ -0,0 +1,91 @@ +// SPDX-License-Identifier: GPL-2.0 +// +// Register map access API - Memory region +// +// This is intended for testing only +// +// Copyright (c) 2023, Arm Ltd + +#include +#include +#include +#include +#include +#include +#include + +#include "internal.h" + +static int regmap_ram_write(void *context, unsigned int reg, unsigned int val) +{ + struct regmap_ram_data *data = context; + + data->vals[reg] = val; + data->written[reg] = true; + + return 0; +} + +static int regmap_ram_read(void *context, unsigned int reg, unsigned int *val) +{ + struct regmap_ram_data *data = context; + + *val = data->vals[reg]; + data->read[reg] = true; + + return 0; +} + +static void regmap_ram_free_context(void *context) +{ + struct regmap_ram_data *data = context; + + kfree(data->vals); + kfree(data->read); + kfree(data->written); + kfree(data); +} + +static const struct regmap_bus regmap_ram = { + .fast_io = true, + .reg_write = regmap_ram_write, + .reg_read = regmap_ram_read, + .free_context = regmap_ram_free_context, +}; + +struct regmap *__regmap_init_ram(struct device *dev, + const struct regmap_config *config, + struct regmap_ram_data *data, + struct lock_class_key *lock_key, + const char *lock_name) +{ + struct regmap *map; + + if (!config->max_register) { + pr_crit("No max_register specified for RAM regmap\n"); + return ERR_PTR(-EINVAL); + } + + data->read = kzalloc_objs(bool, config->max_register + 1); + if (!data->read) + return ERR_PTR(-ENOMEM); + + data->written = kzalloc_objs(bool, config->max_register + 1); + if (!data->written) { + kfree(data->read); + return ERR_PTR(-ENOMEM); + } + + map = __regmap_init(dev, ®map_ram, data, config, + lock_key, lock_name); + if (IS_ERR(map)) { + kfree(data->read); + kfree(data->written); + } + + return map; +} +EXPORT_SYMBOL_GPL(__regmap_init_ram); + +MODULE_DESCRIPTION("Register map access API - Memory region"); +MODULE_LICENSE("GPL v2"); -- cgit v1.3.1