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/Makefile.um | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 73 insertions(+) create mode 100644 arch/x86/Makefile.um (limited to 'arch/x86/Makefile.um') diff --git a/arch/x86/Makefile.um b/arch/x86/Makefile.um new file mode 100644 index 000000000..9adecd656 --- /dev/null +++ b/arch/x86/Makefile.um @@ -0,0 +1,73 @@ +# SPDX-License-Identifier: GPL-2.0 +core-y += arch/x86/crypto/ + +# +# Disable SSE and other FP/SIMD instructions to match normal x86 +# This is required to work around issues in older LLVM versions, but breaks +# GCC versions < 11. See: +# https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99652 +# +ifeq ($(call gcc-min-version, 110000)$(CONFIG_CC_IS_CLANG),y) +KBUILD_CFLAGS += -mno-sse -mno-mmx -mno-sse2 -mno-3dnow -mno-avx +KBUILD_RUSTFLAGS += -Ctarget-feature=-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2 +endif + +KBUILD_RUSTFLAGS += --target=$(objtree)/scripts/target.json + +# The target.json file is not available when invoking rustc-option, so use the +# built-in target when checking whether flags are supported instead. +ifeq ($(CONFIG_X86_32),y) +KBUILD_RUSTFLAGS_OPTION_CHKS += --target=i686-unknown-linux-gnu +else +KBUILD_RUSTFLAGS_OPTION_CHKS += --target=x86_64-unknown-linux-gnu +endif + +ifeq ($(CONFIG_X86_32),y) +START := 0x8048000 + +KBUILD_LDFLAGS += -m elf_i386 +ELF_ARCH := i386 +ELF_FORMAT := elf32-i386 +CHECKFLAGS += -D__i386__ + +KBUILD_CFLAGS += $(call cc-option,-m32) +KBUILD_AFLAGS += $(call cc-option,-m32) +LINK-y += $(call cc-option,-m32) + +LDS_EXTRA := -Ui386 +export LDS_EXTRA + +# First of all, tune CFLAGS for the specific CPU. This actually sets cflags-y. +include $(srctree)/arch/x86/Makefile_32.cpu + +# prevent gcc from keeping the stack 16 byte aligned. Taken from i386. +cflags-y += $(call cc-option,-mpreferred-stack-boundary=2) + +# Prevent sprintf in nfsd from being converted to strcpy and resulting in +# an unresolved reference. +cflags-y += -ffreestanding + +KBUILD_CFLAGS += $(cflags-y) + +else + +START := 0x60000000 + +KBUILD_CFLAGS += -fno-builtin -m64 + +CHECKFLAGS += -m64 -D__x86_64__ +KBUILD_AFLAGS += -m64 +KBUILD_LDFLAGS += -m elf_x86_64 +KBUILD_CPPFLAGS += -m64 + +ELF_ARCH := i386:x86-64 +ELF_FORMAT := elf64-x86-64 + +# Not on all 64-bit distros /lib is a symlink to /lib64. PLD is an example. + +LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib64 +LINK-y += -m64 + +vdso-install-y += arch/x86/um/vdso/vdso.so.dbg + +endif -- cgit v1.3.1