| From a52f8a59aef46b59753e583bf4b28fccb069ce64 Mon Sep 17 00:00:00 2001 |
| From: Kees Cook <keescook@chromium.org> |
| Date: Wed, 12 May 2021 21:51:10 -0700 |
| Subject: fortify: Explicitly disable Clang support |
| |
| From: Kees Cook <keescook@chromium.org> |
| |
| commit a52f8a59aef46b59753e583bf4b28fccb069ce64 upstream. |
| |
| Clang has never correctly compiled the FORTIFY_SOURCE defenses due to |
| a couple bugs: |
| |
| Eliding inlines with matching __builtin_* names |
| https://bugs.llvm.org/show_bug.cgi?id=50322 |
| |
| Incorrect __builtin_constant_p() of some globals |
| https://bugs.llvm.org/show_bug.cgi?id=41459 |
| |
| In the process of making improvements to the FORTIFY_SOURCE defenses, the |
| first (silent) bug (coincidentally) becomes worked around, but exposes |
| the latter which breaks the build. As such, Clang must not be used with |
| CONFIG_FORTIFY_SOURCE until at least latter bug is fixed (in Clang 13), |
| and the fortify routines have been rearranged. |
| |
| Update the Kconfig to reflect the reality of the current situation. |
| |
| Signed-off-by: Kees Cook <keescook@chromium.org> |
| Acked-by: Nick Desaulniers <ndesaulniers@google.com> |
| Link: https://lore.kernel.org/lkml/CAKwvOd=A+ueGV2ihdy5GtgR2fQbcXjjAtVxv3=cPjffpebZB7A@mail.gmail.com |
| Cc: Nathan Chancellor <nathan@kernel.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| security/Kconfig | 3 +++ |
| 1 file changed, 3 insertions(+) |
| |
| --- a/security/Kconfig |
| +++ b/security/Kconfig |
| @@ -191,6 +191,9 @@ 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 |
| help |
| Detect overflows of buffers in common string and memory functions |
| where the compiler can determine and validate the buffer sizes. |
