kbuild: Disable GCOV for *.mod.o

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[ Upstream commit 25a21fbb93 ]

With GCOV_PROFILE_ALL, Clang injects __llvm_gcov_* functions to each
object file, including the *.mod.o. As we filter out CC_FLAGS_CFI
for *.mod.o, the compiler won't generate type hashes for the
injected functions, and therefore indirectly calling them during
module loading trips indirect call checking.

Enabling CFI for *.mod.o isn't sufficient to fix this issue after
commit 0c3e806ec0 ("x86/cfi: Add boot time hash randomization"),
as *.mod.o aren't processed by objtool, which means any hashes
emitted there won't be randomized. Therefore, in addition to
disabling CFI for *.mod.o, also disable GCOV, as the object files
don't otherwise contain any executable code.

Fixes: cf68fffb66 ("add support for Clang CFI")
Reported-by: Joe Fradley <joefradley@google.com>
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

...

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Sami Tolvanen 2023-06-23 00:11:43 +00:00 • committed by Greg Kroah-Hartman

parent cb2d6b93a0

commit 99c515d032

1 changed files with 1 additions and 1 deletions

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