Re: [Qemu-devel] [PATCH] linux-user, s390x: ignore OS ABI value in ELF header

[Thomas Huth]

Am Fri, 10 Nov 2017 20:49:35 +0100
schrieb Laurent Vivier <address@hidden>:

> I have this error:
> bash: /sbin/ldconfig: cannot execute binary file: Exec format error
> 
> because /sbin/ldconfig is:
> ELF 64-bit MSB executable, IBM S/390, version 1 (GNU/Linux),
> statically linked, for GNU/Linux 3.2.0,
> BuildID[sha1]=90b64604014aafac9c1a0623b1cf447281d1a382, stripped
> 
> OS ABI is GNU/linux
> 
> "/bin/ls" works well:
> 
> ELF 64-bit MSB shared object, IBM S/390, version 1 (SYSV),
> dynamically linked, interpreter /lib/ld64.so.1, for GNU/Linux 3.2.0,
> BuildID[sha1]=be9b19143d4657678846f6e5277383071fc1059a, stripped
> 
> OS ABI is SYSV
> 
> To be able to execute ldconfig, this patch modifies s390x binfmt mask
> to ignore the OS ABI value (EI_OSABI, byte 7).
> 
> Signed-off-by: Laurent Vivier <address@hidden>
> ---
>  scripts/qemu-binfmt-conf.sh | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/scripts/qemu-binfmt-conf.sh b/scripts/qemu-binfmt-conf.sh
> index 8afc3eb5bb..e2e1b7544d 100755
> --- a/scripts/qemu-binfmt-conf.sh
> +++ b/scripts/qemu-binfmt-conf.sh
> @@ -85,7 +85,7 @@
> sh4eb_mask='\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff
> sh4eb_family=sh4 
>  
> s390x_magic='\x7fELF\x02\x02\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x02\x00\x16'
> -s390x_mask='\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'
> +s390x_mask='\xff\xff\xff\xff\xff\xff\xff\x00\xff\xff\xff\xff\xff\xff\xff\xff\xff\xfe\xff\xff'

If I've got that right, the OSABI field should either be 0 for
"No extensions or unspecified" (which is then printed  by "file"
as SYSV) or 3 for "GNU/Linux".
Thus wouldn't it be better to use a mask of 0xfc here instead, so
that we refuse at least everything with a value > 3 here?

Also I wonder whether i386 has the same problem, too?

 Thomas