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/x86/entry/Makefile | 26 ++++++++++++++++++++++++++ 1 file changed, 26 insertions(+) create mode 100644 arch/x86/entry/Makefile (limited to 'arch/x86/entry/Makefile') diff --git a/arch/x86/entry/Makefile b/arch/x86/entry/Makefile new file mode 100644 index 000000000..83b4762d6 --- /dev/null +++ b/arch/x86/entry/Makefile @@ -0,0 +1,26 @@ +# SPDX-License-Identifier: GPL-2.0 +# +# Makefile for the x86 low level entry code +# + +KASAN_SANITIZE := n +UBSAN_SANITIZE := n +KCOV_INSTRUMENT := n + +CFLAGS_REMOVE_syscall_32.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_syscall_64.o = $(CC_FLAGS_FTRACE) + +CFLAGS_syscall_32.o += -fno-stack-protector +CFLAGS_syscall_64.o += -fno-stack-protector + +obj-y := entry.o entry_$(BITS).o syscall_$(BITS).o common.o + +obj-y += vdso/ +obj-y += vsyscall/ + +obj-$(CONFIG_PREEMPTION) += thunk.o +CFLAGS_entry_fred.o += -fno-stack-protector +CFLAGS_REMOVE_entry_fred.o += -pg $(CC_FLAGS_FTRACE) +obj-$(CONFIG_X86_FRED) += entry_64_fred.o entry_fred.o + +obj-$(CONFIG_IA32_EMULATION) += entry_64_compat.o syscall_32.o -- cgit v1.3.1