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Date: Fri, 19 Jun 2026 13:44:43 -0700
From: Kees Cook <kees@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Sami Tolvanen <samitolvanen@google.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Arnd Bergmann <arnd@arndb.de>,
	Brendan Higgins <brendan.higgins@linux.dev>,
	David Gow <david@davidgow.net>, Rae Moar <raemoar63@gmail.com>,
	llvm@lists.linux.dev, kunit-dev@googlegroups.com,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: Re: [PATCH v2] kunit: cfi: Add test for kCFI indirect-call type
 checks
Message-ID: <202606191342.E2B47A5@keescook>
References: <20260618210946.it.538-kees@kernel.org>
 <20260619093708.GT49951@noisy.programming.kicks-ass.net>
 <20260619095129.GE49529@noisy.programming.kicks-ass.net>
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In-Reply-To: <20260619095129.GE49529@noisy.programming.kicks-ass.net>

On Fri, Jun 19, 2026 at 11:51:29AM +0200, Peter Zijlstra wrote:
> > This is really rather horrible. Also, now all an attacker needs to do is
> > ensure cfi_kunit_handled() unconditionally returns true. IOW, no distro
> > must ever have this KUNIT crap enabled.
> 
> Also, if this lives, the check should at least trip the cfi_warn path,
> being completely silent is terrible.

If anyone actually ships kunit in production, then no, I will NAK my own
patch. ;) In that case I will go back to a version I never sent, which
uses Kunit's try/catch Oops checker (which doesn't work on riscv). I
only did it this way (similar to the fortify kunit testing) so I could
get riscv coverage.

-- 
Kees Cook