| Message ID | 20210822075122.864511-17-keescook@chromium.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Prepare for better FORTIFY_SOURCE | expand |
On Sun, Aug 22, 2021 at 12:57 AM Kees Cook <keescook@chromium.org> wrote: > > 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> > --- > security/Kconfig | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/security/Kconfig b/security/Kconfig > index 0ced7fd33e4d..fe6c0395fa02 100644 > --- 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. > -- > 2.30.2 > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210822075122.864511-17-keescook%40chromium.org.
diff --git a/security/Kconfig b/security/Kconfig index 0ced7fd33e4d..fe6c0395fa02 100644 --- 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.
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> --- security/Kconfig | 3 +++ 1 file changed, 3 insertions(+)