[PATCH 5.15 716/731] security: Restrict CONFIG_ZERO_CALL_USED_REGS to gcc or clang > 15.0.6

Greg Kroah-Hartman
2022-12-28T16:03:12Z

From: Nathan Chancellor <nathan@kernel.org>

commit d6a9fb87e9d18f3394a9845546bbe868efdccfd2 upstream.

A bad bug in clang's implementation of -fzero-call-used-regs can result
in NULL pointer dereferences (see the links above the check for more
information). Restrict CONFIG_CC_HAS_ZERO_CALL_USED_REGS to either a
supported GCC version or a clang newer than 15.0.6, which will catch
both a theoretical 15.0.7 and the upcoming 16.0.0, which will both have
the bug fixed.

Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221214232602.4118147-1-nathan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
security/Kconfig.hardening | 3 +++
1 file changed, 3 insertions(+)

--- a/security/Kconfig.hardening
+++ b/security/Kconfig.hardening
@@ -240,6 +240,9 @@ config INIT_ON_FREE_DEFAULT_ON

config CC_HAS_ZERO_CALL_USED_REGS
def_bool $(cc-option,-fzero-call-used-regs=used-gpr)
+ # https://github.com/ClangBuiltLinux/linux/issues/1766
+ # https://github.com/llvm/llvm-project/issues/59242
+ depends on !CC_IS_CLANG || CLANG_VERSION > 150006

config ZERO_CALL_USED_REGS
bool "Enable register zeroing on function exit"