lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Mon, 16 Jan 2017 22:42:29 +1100
From:   Anton Blanchard <>
To:     Peter Zijlstra <>
        Segher Boessenkool <>,,,
Subject: Re: llist code relies on undefined behaviour, upsets llvm/clang

Hi Peter,

> Last I checked I couldn't build a x86_64 kernel with llvm. So no, not
> something I've ever ran into.
> Also, I would argue that this is broken in llvm, the kernel very much
> relies on things like this all over the place. Sure, we're way outside
> of what the C language spec says, but who bloody cares ;-)

True, but is there anything preventing gcc from implementing this
optimisation in the future? If we are relying on undefined behaviour we
should have a -fno-strict-* option to cover it.

> If llvm wants to compile the kernel, it needs to learn the C dialect
> the kernel uses.

LLVM has done that before (eg adding -fno-strict-overflow). I don't
think that option covers this case however.


Powered by blists - more mailing lists