From 281d0c962752fb40866dd8d4cade68656f34bd1f Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 8 Feb 2022 14:53:50 -0800 Subject: fortify: Add Clang support Enable FORTIFY_SOURCE support for Clang: Use the new __pass_object_size and __overloadable attributes so that Clang will have appropriate visibility into argument sizes such that __builtin_object_size(p, 1) will behave correctly. Additional details available here: https://github.com/llvm/llvm-project/issues/53516 https://github.com/ClangBuiltLinux/linux/issues/1401 A bug with __builtin_constant_p() of globally defined variables was fixed in Clang 13 (and backported to 12.0.1), so FORTIFY support must depend on that version or later. Additional details here: https://bugs.llvm.org/show_bug.cgi?id=41459 commit a52f8a59aef4 ("fortify: Explicitly disable Clang support") A bug with Clang's -mregparm=3 and -m32 makes some builtins unusable, so removing -ffreestanding (to gain the needed libcall optimizations with Clang) cannot be done. Without the libcall optimizations, Clang cannot provide appropriate FORTIFY coverage, so it must be disabled for CONFIG_X86_32. Additional details here; https://github.com/llvm/llvm-project/issues/53645 Cc: Miguel Ojeda Cc: Nick Desaulniers Cc: Nathan Chancellor Cc: George Burgess IV Cc: llvm@lists.linux.dev Signed-off-by: Kees Cook Reviewed-by: Nick Desaulniers Link: https://lore.kernel.org/r/20220208225350.1331628-9-keescook@chromium.org --- security/Kconfig | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'security/Kconfig') diff --git a/security/Kconfig b/security/Kconfig index 0b847f435beb..1d2d71cc1f36 100644 --- a/security/Kconfig +++ b/security/Kconfig @@ -177,9 +177,10 @@ config HARDENED_USERCOPY_PAGESPAN config FORTIFY_SOURCE bool "Harden common str/mem functions against buffer overflows" depends on ARCH_HAS_FORTIFY_SOURCE - # https://bugs.llvm.org/show_bug.cgi?id=50322 # https://bugs.llvm.org/show_bug.cgi?id=41459 - depends on !CC_IS_CLANG + depends on !CC_IS_CLANG || CLANG_VERSION >= 120001 + # https://github.com/llvm/llvm-project/issues/53645 + depends on !CC_IS_CLANG || !X86_32 help Detect overflows of buffers in common string and memory functions where the compiler can determine and validate the buffer sizes. -- cgit v1.2.3