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From: Kees Cook <>
To: Nathan Chancellor <>
Subject: Re: [PATCH v2 2/2] kbuild: Enable -Wincompatible-function-pointer-types-strict in W=1
Date: Wed, 6 Dec 2023 12:31:05 -0800	[thread overview]
Message-ID: <202312061230.DCDD958@keescook> (raw)
In-Reply-To: <>

On Wed, Dec 06, 2023 at 09:49:47AM -0700, Nathan Chancellor wrote:
> -Wincompatible-function-pointer-types-strict aims to catch clang kernel
> Control Flow Integrity (kCFI) violations at build time (rather than run
> time) by validating function pointer assignments against the expected
> prototype, similar to the existing -Wincompatible-function-pointer-types
> that is considered a hard error in the kernel. The -strict variant
> requires the types to match exactly, as opposed to just matching in
> terms of ABI compatibility. This is primarily visible with int/unsigned
> int in lieu of enum types or vice versa.
> The tree is not completely clean, so this warning cannot currently be
> enabled unconditionally. However, there are only warnings in one
> subsystem ('drivers/counter'), so it is really close. In order to
> benefit from CI infrastructure that tests with W=1, enable this warning
> at that level, so that new instances have a chance of being caught and
> fixed during development.
> This should eventually be a hard error in a similar manner as
> Wincompatible-function-pointer-types but some subsystems test
> with W=1 + CONFIG_WERROR=n, so it would be rude to break their builds
> when they do not care about warnings outside of their subsystem.
> Link:
> Reviewed-by: Nick Desaulniers <>
> Signed-off-by: Nathan Chancellor <>

Keeping these from leaking in is always good. Thanks!

Reviewed-by: Kees Cook <>

Kees Cook

      reply	other threads:[~2023-12-06 20:31 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-12-06 16:49 [PATCH v2 0/2] Enable -Wincompatible-function-pointer-types-strict under W=1 Nathan Chancellor
2023-12-06 16:49 ` [PATCH v2 1/2] um: net: Fix return type of uml_net_start_xmit() Nathan Chancellor
2023-12-06 20:30   ` Kees Cook
2023-12-06 16:49 ` [PATCH v2 2/2] kbuild: Enable -Wincompatible-function-pointer-types-strict in W=1 Nathan Chancellor
2023-12-06 20:31   ` Kees Cook [this message]

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