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 --- arch/powerpc/lib/pmem.c | 88 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 arch/powerpc/lib/pmem.c (limited to 'arch/powerpc/lib/pmem.c') diff --git a/arch/powerpc/lib/pmem.c b/arch/powerpc/lib/pmem.c new file mode 100644 index 000000000..0f0f2d851 --- /dev/null +++ b/arch/powerpc/lib/pmem.c @@ -0,0 +1,88 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright(c) 2017 IBM Corporation. All rights reserved. + */ + +#include +#include +#include +#include + +#include + +static inline void __clean_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBSTPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void __flush_pmem_range(unsigned long start, unsigned long stop) +{ + unsigned long shift = l1_dcache_shift(); + unsigned long bytes = l1_dcache_bytes(); + void *addr = (void *)(start & ~(bytes - 1)); + unsigned long size = stop - (unsigned long)addr + (bytes - 1); + unsigned long i; + + for (i = 0; i < size >> shift; i++, addr += bytes) + asm volatile(PPC_DCBFPS(%0, %1): :"i"(0), "r"(addr): "memory"); +} + +static inline void clean_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __clean_pmem_range(start, stop); +} + +static inline void flush_pmem_range(unsigned long start, unsigned long stop) +{ + if (cpu_has_feature(CPU_FTR_ARCH_207S)) + return __flush_pmem_range(start, stop); +} + +/* + * CONFIG_ARCH_HAS_PMEM_API symbols + */ +void arch_wb_cache_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_wb_cache_pmem); + +void arch_invalidate_pmem(void *addr, size_t size) +{ + unsigned long start = (unsigned long) addr; + flush_pmem_range(start, start + size); +} +EXPORT_SYMBOL_GPL(arch_invalidate_pmem); + +/* + * CONFIG_ARCH_HAS_UACCESS_FLUSHCACHE symbols + */ +size_t copy_from_user_flushcache(void *dest, const void __user *src, + size_t size) +{ + unsigned long not_copied, start = (unsigned long) dest; + + src = mask_user_address(src); + not_copied = __copy_from_user(dest, src, size); + clean_pmem_range(start, start + size); + + return not_copied; +} + +void memcpy_flushcache(void *dest, const void *src, size_t size) +{ + unsigned long start = (unsigned long) dest; + + memcpy(dest, src, size); + clean_pmem_range(start, start + size); +} +EXPORT_SYMBOL(memcpy_flushcache); -- cgit v1.3.1