Re: [PATCH for 4.4, 4.9 and 4.14] x86/vdso: Pass --eh-frame-hdr to the linker

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

On Tue, May 14, 2019 at 04:34:29PM +0900, Nobuhiro Iwamatsu wrote:
> From: Alistair Strachan <astrachan@google.com>
> 
> commit cd01544a268ad8ee5b1dfe42c4393f1095f86879 upstream.
> 
> Commit
> 
>   379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link")
> 
> accidentally broke unwinding from userspace, because ld would strip the
> .eh_frame sections when linking.
> 
> Originally, the compiler would implicitly add --eh-frame-hdr when
> invoking the linker, but when this Makefile was converted from invoking
> ld via the compiler, to invoking it directly (like vmlinux does),
> the flag was missed. (The EH_FRAME section is important for the VDSO
> shared libraries, but not for vmlinux.)
> 
> Fix the problem by explicitly specifying --eh-frame-hdr, which restores
> parity with the old method.
> 
> See relevant bug reports for additional info:
> 
>   https://bugzilla.kernel.org/show_bug.cgi?id=201741
>   https://bugzilla.redhat.com/show_bug.cgi?id=1659295
> 
> Fixes: 379d98ddf413 ("x86: vdso: Use $LD instead of $CC to link")
> Reported-by: Florian Weimer <fweimer@redhat.com>
> Reported-by: Carlos O'Donell <carlos@redhat.com>
> Reported-by: "H. J. Lu" <hjl.tools@gmail.com>
> Signed-off-by: Alistair Strachan <astrachan@google.com>
> Signed-off-by: Borislav Petkov <bp@suse.de>
> Tested-by: Laura Abbott <labbott@redhat.com>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Carlos O'Donell <carlos@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Joel Fernandes <joel@joelfernandes.org>
> Cc: kernel-team@android.com
> Cc: Laura Abbott <labbott@redhat.com>
> Cc: stable <stable@vger.kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: X86 ML <x86@kernel.org>
> Link: https://lkml.kernel.org/r/20181214223637.35954-1-astrachan@google.com
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> ---
>  arch/x86/entry/vdso/Makefile | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

This is already in the 4.14 stable queue.

Sasha, how did you tools miss it for 4.4 and 4.9?

thanks,

greg k-h