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authorSami Tolvanen <samitolvanen@google.com>2023-01-12 22:49:48 +0000
committerKees Cook <keescook@chromium.org>2023-01-13 15:22:03 -0800
commit42633ed852deadc14d44660ad71e2f6640239120 (patch)
treef310289c78f17243391c6af27d149ba4961c746c
parent3b293487b8752cc42c1cbf8a0447bc6076c075fa (diff)
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kbuild: Fix CFI hash randomization with KASAN
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 commit 0c3e806ec0f9 ("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: 0c3e806ec0f9 ("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
-rw-r--r--init/Makefile1
-rw-r--r--scripts/Makefile.vmlinux1
2 files changed, 2 insertions, 0 deletions
diff --git a/init/Makefile b/init/Makefile
index 8316c23bead2..26de459006c4 100644
--- a/init/Makefile
+++ b/init/Makefile
@@ -59,3 +59,4 @@ include/generated/utsversion.h: FORCE
$(obj)/version-timestamp.o: include/generated/utsversion.h
CFLAGS_version-timestamp.o := -include include/generated/utsversion.h
+KASAN_SANITIZE_version-timestamp.o := n
diff --git a/scripts/Makefile.vmlinux b/scripts/Makefile.vmlinux
index 49946cb96844..10176dec97ea 100644
--- a/scripts/Makefile.vmlinux
+++ b/scripts/Makefile.vmlinux
@@ -18,6 +18,7 @@ quiet_cmd_cc_o_c = CC $@
$(call if_changed_dep,cc_o_c)
ifdef CONFIG_MODULES
+KASAN_SANITIZE_.vmlinux.export.o := n
targets += .vmlinux.export.o
vmlinux: .vmlinux.export.o
endif