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/dca/dca-sysfs.c | 94 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) create mode 100644 drivers/dca/dca-sysfs.c (limited to 'drivers/dca/dca-sysfs.c') diff --git a/drivers/dca/dca-sysfs.c b/drivers/dca/dca-sysfs.c new file mode 100644 index 000000000..b915c2b46 --- /dev/null +++ b/drivers/dca/dca-sysfs.c @@ -0,0 +1,94 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright(c) 2007 - 2009 Intel Corporation. All rights reserved. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static const struct class dca_class = { + .name = "dca", +}; +static struct idr dca_idr; +static spinlock_t dca_idr_lock; + +int dca_sysfs_add_req(struct dca_provider *dca, struct device *dev, int slot) +{ + struct device *cd; + static int req_count; + + cd = device_create(&dca_class, dca->cd, MKDEV(0, slot + 1), NULL, + "requester%d", req_count++); + return PTR_ERR_OR_ZERO(cd); +} + +void dca_sysfs_remove_req(struct dca_provider *dca, int slot) +{ + device_destroy(&dca_class, MKDEV(0, slot + 1)); +} + +int dca_sysfs_add_provider(struct dca_provider *dca, struct device *dev) +{ + struct device *cd; + int ret; + + idr_preload(GFP_KERNEL); + spin_lock(&dca_idr_lock); + + ret = idr_alloc(&dca_idr, dca, 0, 0, GFP_NOWAIT); + if (ret >= 0) + dca->id = ret; + + spin_unlock(&dca_idr_lock); + idr_preload_end(); + if (ret < 0) + return ret; + + cd = device_create(&dca_class, dev, MKDEV(0, 0), NULL, "dca%d", dca->id); + if (IS_ERR(cd)) { + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); + return PTR_ERR(cd); + } + dca->cd = cd; + return 0; +} + +void dca_sysfs_remove_provider(struct dca_provider *dca) +{ + device_unregister(dca->cd); + dca->cd = NULL; + spin_lock(&dca_idr_lock); + idr_remove(&dca_idr, dca->id); + spin_unlock(&dca_idr_lock); +} + +int __init dca_sysfs_init(void) +{ + int err; + + idr_init(&dca_idr); + spin_lock_init(&dca_idr_lock); + + err = class_register(&dca_class); + if (err) { + idr_destroy(&dca_idr); + return err; + } + return 0; +} + +void __exit dca_sysfs_exit(void) +{ + class_unregister(&dca_class); + idr_destroy(&dca_idr); +} + -- cgit v1.3.1