Re: [PATCH 6.6.y 0/6] Backported patches to fix selftest tpdir2

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, Apr 02, 2025 at 04:26:50PM +0800, Kang Wenlin wrote:
> From: Wenlin Kang <wenlin.kang@windriver.com>
> 
> The selftest tpdir2 terminated with a 'Segmentation fault' during loading. 
> 
> root@localhost:~# cd linux-kenel/tools/testing/selftests/arm64/abi && make
> root@localhost:~/linux-kernel/tools/testing/selftests/arm64/abi# ./tpidr2
> Segmentation fault
> 
> The cause of this is the __arch_clear_user() failure.
> 
> load_elf_binary() [fs/binfmt_elf.c]
>   -> if (likely(elf_bss != elf_brk) && unlikely(padzero(elf_bes)))
>     -> padzero()
>       -> clear_user() [arch/arm64/include/asm/uaccess.h]
>         -> __arch_clear_user() [arch/arm64/lib/clear_user.S]
> 
> For more details, please see:
> https://lore.kernel.org/lkml/1d0342f3-0474-482b-b6db-81ca7820a462@t-8ch.de/T/

This is just a userspace issue (i.e. don't do that, and if you do want
to do that, use a new kernel!)

Why do these changes need to be backported, do you have real users that
are crashing in this way to require these changes?

thanks,

greg k-h