From: Sami Tolvanen samitolvanen@google.com
[ Upstream commit 25a21fbb934a0d989e1858f83c2ddf4cfb2ebe30 ]
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 0c3e806ec0f9 ("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: cf68fffb66d6 ("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 --- scripts/Makefile.modfinal | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/scripts/Makefile.modfinal b/scripts/Makefile.modfinal index 4703f652c0098..fc19f67039bda 100644 --- a/scripts/Makefile.modfinal +++ b/scripts/Makefile.modfinal @@ -23,7 +23,7 @@ modname = $(notdir $(@:.mod.o=)) part-of-module = y
quiet_cmd_cc_o_c = CC [M] $@ - cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI), $(c_flags)) -c -o $@ $< + cmd_cc_o_c = $(CC) $(filter-out $(CC_FLAGS_CFI) $(CFLAGS_GCOV), $(c_flags)) -c -o $@ $<
%.mod.o: %.mod.c FORCE $(call if_changed_dep,cc_o_c)