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

[Sasha Levin <sashal@kernel.org>]

On Tue, May 14, 2019 at 02:39:22PM +0200, Greg Kroah-Hartman wrote:
>On Tue, May 14, 2019 at 08:32:49AM -0400, Sasha Levin wrote:
>> On Tue, May 14, 2019 at 09:50:04AM +0200, Greg Kroah-Hartman wrote:
>> > 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?
>>
>> This commit claims it fixes 379d98ddf413 ("x86: vdso: Use $LD instead of
>> $CC to link"), which is not in 4.9 nor 4.4
>
>It's already in 4.4.179 :(
>I think you need to adjust your scripts, you signed off on the backport :)
>I guess we need to also add it to 4.9.y?

Ah, it came in via the android folks as a patchset for 4.4.

Yes, we should get all branches synced up here, I can do it if you
haven't yet :)

--
Thanks,
Sasha