rust: SHADOW_CALL_STACK is incompatible with Rust

commit f126745da81783fb1d082e67bf14c6795e489a88 upstream.

When using the shadow call stack sanitizer, all code must be compiled
with the -ffixed-x18 flag, but this flag is not currently being passed
to Rust. This results in crashes that are extremely difficult to debug.

To ensure that nobody else has to go through the same debugging session
that I had to, prevent configurations that enable both SHADOW_CALL_STACK
and RUST.

It is rather common for people to backport 724a75ac9542 ("arm64: rust:
Enable Rust support for AArch64"), so I recommend applying this fix all
the way back to 6.1.

Cc: stable@vger.kernel.org # 6.1 and later
Fixes: 724a75ac9542 ("arm64: rust: Enable Rust support for AArch64")
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Acked-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20240729-shadow-call-stack-v4-1-2a664b082ea4@google.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/init/Kconfig b/init/Kconfig
index febdea2afc3be3ffeeb2029386ea931f364dec1c..d8a971b804d328a99e4e1ccf86478d40cced9521 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1906,6 +1906,7 @@ config RUST
        depends on !MODVERSIONS
        depends on !GCC_PLUGINS
        depends on !RANDSTRUCT
+       depends on !SHADOW_CALL_STACK
        depends on !DEBUG_INFO_BTF || PAHOLE_HAS_LANG_EXCLUDE
        help
          Enables Rust support in the kernel.