Add -Zsanitize=kernel-hwaddress

[Darksonn]

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The Linux kernel has a config option called CONFIG_KASAN_SW_TAGS that enables -fsanitize=kernel-hwaddress. This is not supported by Rust.

One slightly awkward detail is that #[sanitize(address = "off")] applies to both -Zsanitize=address and -Zsanitize=kernel-address. Probably it was done this way because both are the same LLVM pass. I replicated this logic here for hwaddress, but it might be undesirable.

Note that #[sanitize(kernel_hwaddress = "off")] could be supported as an annotation on statics, but since it's also missing for #[sanitize(hwaddress = "off")], I did not add it.

MCP: rust-lang/compiler-team#975

cc @rcvalle @maurer @ojeda

[Darksonn]

@fmayer Is this reasonable a reasonable fix for rustc to work around the lack of llvm/llvm-project#142226? Or do you think I should pass this on all versions? Thanks!

[rustbot]

Some changes occurred in cfg and check-cfg configuration

cc @Urgau

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

Some changes occurred in src/tools/compiletest

cc @jieyouxu

Some changes occurred in tests/codegen-llvm/sanitizer

cc @rcvalle

Some changes occurred in compiler/rustc_attr_parsing

cc @jdonszelmann, @JonathanBrouwer

[rustbot]

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[rcvalle]

cc @1c3t3a @jakos-sec

[mati865]

FYI LLVM prior to 21 is no longer supported: #153684

[Darksonn]

@mati865 Technically bug also occurs on 21.0, as it wasn't fixed until 21.1.0

[mati865]

@Darksonn sorry if it wasn't clear. LLVM uses X.1.0 for the first release of each major version and there is no such version as LLVM 21.0.0. So by saying LLVM 21 I meant LLVM >=21.1.0 since this is the first release of that major version.

Thus, LLVM 21.1.0 is the oldest supported version now.

[Darksonn]

@mati865 Oh I did not know that. In that case, I can take out the bugfix.

For posterity, it add this to compiler/rustc_codegen_llvm/src/llvm_util.rs

        // KHWASAN: In LLVM versions prior to 21.1.0, the HWAddressSanitizer pass incorrectly
        // ignores the pass-specific `CompileKernel` flag and only looks at the global command-line
        // flag `-hwasan-kernel`. To work around this, pass `-hwasan-kernel` on the relevant LLVM
        // versions.
        //
        // Fixed by: [HWASan][bugfix] Fix kernel check in ShadowMapping::init (#142226).
        if sess.sanitizers().contains(SanitizerSet::KERNELHWADDRESS) && get_version() < (21, 1, 0) {
            add("-hwasan-kernel", false);
        }

[rustbot]

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

[Darksonn]

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