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Clang emits a asan.module_ctor constructor to each object file when KASAN is enabled, and these functions are indirectly called in do_ctors. With CONFIG_CFI_CLANG, the compiler also emits a CFI type hash before each address-taken global function so they can pass indirect call checks. However, in commit0c3e806ec0("x86/cfi: Add boot time hash randomization"), x86 implemented boot time hash randomization, which relies on the .cfi_sites section generated by objtool. As objtool is run against vmlinux.o instead of individual object files with X86_KERNEL_IBT (enabled by default), CFI types in object files that are not part of vmlinux.o end up not being included in .cfi_sites, and thus won't get randomized and trip CFI when called. Only .vmlinux.export.o and init/version-timestamp.o are linked into vmlinux separately from vmlinux.o. As these files don't contain any functions, disable KASAN for both of them to avoid breaking hash randomization. Link: https://github.com/ClangBuiltLinux/linux/issues/1742 Fixes:0c3e806ec0("x86/cfi: Add boot time hash randomization") Signed-off-by: Sami Tolvanen <samitolvanen@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20230112224948.1479453-2-samitolvanen@google.com
53 lines
1.4 KiB
Makefile
53 lines
1.4 KiB
Makefile
# SPDX-License-Identifier: GPL-2.0-only
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PHONY := __default
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__default: vmlinux
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include include/config/auto.conf
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include $(srctree)/scripts/Kbuild.include
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# for c_flags
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include $(srctree)/scripts/Makefile.lib
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targets :=
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quiet_cmd_cc_o_c = CC $@
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cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<
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%.o: %.c FORCE
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$(call if_changed_dep,cc_o_c)
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ifdef CONFIG_MODULES
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KASAN_SANITIZE_.vmlinux.export.o := n
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targets += .vmlinux.export.o
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vmlinux: .vmlinux.export.o
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endif
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ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink)
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# Final link of vmlinux with optional arch pass after final link
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cmd_link_vmlinux = \
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$< "$(LD)" "$(KBUILD_LDFLAGS)" "$(LDFLAGS_vmlinux)"; \
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$(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)
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targets += vmlinux
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vmlinux: scripts/link-vmlinux.sh vmlinux.o $(KBUILD_LDS) FORCE
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+$(call if_changed_dep,link_vmlinux)
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# Add FORCE to the prequisites of a target to force it to be always rebuilt.
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# ---------------------------------------------------------------------------
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PHONY += FORCE
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FORCE:
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# Read all saved command lines and dependencies for the $(targets) we
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# may be building above, using $(if_changed{,_dep}). As an
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# optimization, we don't need to read them if the target does not
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# exist, we will rebuild anyway in that case.
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existing-targets := $(wildcard $(sort $(targets)))
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-include $(foreach f,$(existing-targets),$(dir $(f)).$(notdir $(f)).cmd)
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.PHONY: $(PHONY)
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