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Date:   Tue, 5 Sep 2023 11:21:03 +0100
From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     Lukas Bulwahn <lukas.bulwahn@gmail.com>
Cc:     Andrey Ryabinin <aryabinin@virtuozzo.com>,
        Andrey Ryabinin <ryabinin.a.a@gmail.com>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nathan Chancellor <nathan@kernel.org>,
        Sasha Levin <sashal@kernel.org>,
        kasan-dev <kasan-dev@googlegroups.com>, llvm@lists.linux.dev,
        linux- stable <stable@vger.kernel.org>,
        Alexander Potapenko <glider@google.com>,
        Andrey Konovalov <andreyknvl@gmail.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        Vincenzo Frascino <vincenzo.frascino@arm.com>,
        eb-gft-team@globallogic.com
Subject: Re: Include bac7a1fff792 ("lib/ubsan: remove
 returns-nonnull-attribute checks") into linux-4.14.y
Message-ID: <2023090548-flattery-wrath-8ace@gregkh>
References: <CAKXUXMzR4830pmUfWnwVjGk94inpQ0iz_uXiOnrE2kyV7SUPpg@mail.gmail.com>
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On Tue, Sep 05, 2023 at 12:12:11PM +0200, Lukas Bulwahn wrote:
> Dear Andrey, dear Nick, dear Greg, dear Sasha,
> 
> 
> Compiling the kernel with UBSAN enabled and with gcc-8 and later fails when:
> 
>   commit 1e1b6d63d634 ("lib/string.c: implement stpcpy") is applied, and
>   commit bac7a1fff792 ("lib/ubsan: remove returns-nonnull-attribute checks") is
>   not applied.
> 
> To reproduce, run:
> 
>   tuxmake -r docker -a arm64 -t gcc-13 -k allnoconfig --kconfig-add
> CONFIG_UBSAN=y
> 
> It then fails with:
> 
>   aarch64-linux-gnu-ld: lib/string.o: in function `stpcpy':
>   string.c:(.text+0x694): undefined reference to
> `__ubsan_handle_nonnull_return_v1'
>   string.c:(.text+0x694): relocation truncated to fit:
> R_AARCH64_CALL26 against undefined symbol
> `__ubsan_handle_nonnull_return_v1'
> 
> Below you find a complete list of architectures, compiler versions and kernel
> versions that I have tested with.
> 
> As commit bac7a1fff792 ("lib/ubsan: remove returns-nonnull-attribute checks") is
> included in v4.16, and commit 1e1b6d63d634 ("lib/string.c: implement stpcpy") is
> included in v5.9, this is not an issue that can happen on any mainline release
> or the stable releases v4.19.y and later.
> 
> In the v4.14.y branch, however, commit 1e1b6d63d634 ("lib/string.c: implement
> stpcpy") was included with v4.14.200 as commit b6d38137c19f and commit
> bac7a1fff792 ("lib/ubsan: remove returns-nonnull-attribute checks") from
> mainline was not included yet. Hence, this reported failure with UBSAN can be
> observed on v4.14.y with recent gcc versions.
> 
> Greg, once checked and confirmed by Andrey or Nick, could you please include
> commit bac7a1fff792 ("lib/ubsan: remove returns-nonnull-attribute checks") into
> the linux-4.14.y branch?

Now queued up, thanks.

greg k-h