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| author | Sami Tolvanen <samitolvanen@google.com> | 2023-01-12 22:49:48 +0000 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2023-01-13 15:22:03 -0800 |
| commit | 42633ed852deadc14d44660ad71e2f6640239120 (patch) | |
| tree | f310289c78f17243391c6af27d149ba4961c746c /init | |
| parent | 3b293487b8752cc42c1cbf8a0447bc6076c075fa (diff) | |
| download | lwn-42633ed852deadc14d44660ad71e2f6640239120.tar.gz lwn-42633ed852deadc14d44660ad71e2f6640239120.zip | |
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
Diffstat (limited to 'init')
| -rw-r--r-- | init/Makefile | 1 |
1 files changed, 1 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 |