fortify: Explicitly disable Clang support
authorKees Cook <keescook@chromium.org>
Thu, 13 May 2021 04:51:10 +0000 (21:51 -0700)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sun, 21 Nov 2021 12:46:35 +0000 (13:46 +0100)
commiteaafc590053b314d4907017044ba2e739893c17c
tree710f07572297f67f2537a5d49463ba1fee81ef33
parentf884bb85b8d877d4e0c670403754813a7901705b
fortify: Explicitly disable Clang support

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