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/arm/mm/physaddr.c | 58 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 58 insertions(+) create mode 100644 arch/arm/mm/physaddr.c (limited to 'arch/arm/mm/physaddr.c') diff --git a/arch/arm/mm/physaddr.c b/arch/arm/mm/physaddr.c new file mode 100644 index 000000000..1a37ebfac --- /dev/null +++ b/arch/arm/mm/physaddr.c @@ -0,0 +1,58 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include +#include +#include + +#include +#include +#include +#include + +#include "mm.h" + +static inline bool __virt_addr_valid(unsigned long x) +{ + /* + * high_memory does not get immediately defined, and there + * are early callers of __pa() against PAGE_OFFSET + */ + if (!high_memory && x >= PAGE_OFFSET) + return true; + + if (high_memory && x >= PAGE_OFFSET && x < (unsigned long)high_memory) + return true; + + /* + * MAX_DMA_ADDRESS is a virtual address that may not correspond to an + * actual physical address. Enough code relies on __pa(MAX_DMA_ADDRESS) + * that we just need to work around it and always return true. + */ + if (x == MAX_DMA_ADDRESS) + return true; + + return false; +} + +phys_addr_t __virt_to_phys(unsigned long x) +{ + WARN(!__virt_addr_valid(x), + "virt_to_phys used for non-linear address: %px (%pS)\n", + (void *)x, (void *)x); + + return __virt_to_phys_nodebug(x); +} +EXPORT_SYMBOL(__virt_to_phys); + +phys_addr_t __phys_addr_symbol(unsigned long x) +{ + /* This is bounds checking against the kernel image only. + * __pa_symbol should only be used on kernel symbol addresses. + */ + VIRTUAL_BUG_ON(x < (unsigned long)KERNEL_START || + x > (unsigned long)KERNEL_END); + + return __pa_symbol_nodebug(x); +} +EXPORT_SYMBOL(__phys_addr_symbol); -- cgit v1.3.1