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/arch/arm/include/asm/barrier.h | 12 ++++++++++++ tools/arch/arm/include/uapi/asm/mman.h | 7 +++++++ tools/arch/arm/include/uapi/asm/perf_regs.h | 24 ++++++++++++++++++++++++ 3 files changed, 43 insertions(+) create mode 100644 tools/arch/arm/include/asm/barrier.h create mode 100644 tools/arch/arm/include/uapi/asm/mman.h create mode 100644 tools/arch/arm/include/uapi/asm/perf_regs.h (limited to 'tools/arch/arm/include') diff --git a/tools/arch/arm/include/asm/barrier.h b/tools/arch/arm/include/asm/barrier.h new file mode 100644 index 000000000..005c618a0 --- /dev/null +++ b/tools/arch/arm/include/asm/barrier.h @@ -0,0 +1,12 @@ +#ifndef _TOOLS_LINUX_ASM_ARM_BARRIER_H +#define _TOOLS_LINUX_ASM_ARM_BARRIER_H + +/* + * Use the __kuser_memory_barrier helper in the CPU helper page. See + * arch/arm/kernel/entry-armv.S in the kernel source for details. + */ +#define mb() ((void(*)(void))0xffff0fa0)() +#define wmb() ((void(*)(void))0xffff0fa0)() +#define rmb() ((void(*)(void))0xffff0fa0)() + +#endif /* _TOOLS_LINUX_ASM_ARM_BARRIER_H */ diff --git a/tools/arch/arm/include/uapi/asm/mman.h b/tools/arch/arm/include/uapi/asm/mman.h new file mode 100644 index 000000000..a6d46321e --- /dev/null +++ b/tools/arch/arm/include/uapi/asm/mman.h @@ -0,0 +1,7 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef TOOLS_ARCH_ARM_UAPI_ASM_MMAN_FIX_H +#define TOOLS_ARCH_ARM_UAPI_ASM_MMAN_FIX_H +#include +/* MAP_32BIT is undefined on arm, fix it for perf */ +#define MAP_32BIT 0 +#endif diff --git a/tools/arch/arm/include/uapi/asm/perf_regs.h b/tools/arch/arm/include/uapi/asm/perf_regs.h new file mode 100644 index 000000000..a3c046174 --- /dev/null +++ b/tools/arch/arm/include/uapi/asm/perf_regs.h @@ -0,0 +1,24 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _ASM_ARM_PERF_REGS_H +#define _ASM_ARM_PERF_REGS_H + +enum perf_event_arm_regs { + PERF_REG_ARM_R0, + PERF_REG_ARM_R1, + PERF_REG_ARM_R2, + PERF_REG_ARM_R3, + PERF_REG_ARM_R4, + PERF_REG_ARM_R5, + PERF_REG_ARM_R6, + PERF_REG_ARM_R7, + PERF_REG_ARM_R8, + PERF_REG_ARM_R9, + PERF_REG_ARM_R10, + PERF_REG_ARM_FP, + PERF_REG_ARM_IP, + PERF_REG_ARM_SP, + PERF_REG_ARM_LR, + PERF_REG_ARM_PC, + PERF_REG_ARM_MAX, +}; +#endif /* _ASM_ARM_PERF_REGS_H */ -- cgit v1.3.1