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
