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

[Nathan Chancellor <natechancellor@gmail.com>]

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?

Not Sasha's fault but mine, I forgot to git grep for the short hash like
I usually do to ensure I catch all fixes (or I didn't do it properly, I
forget which) when I added this to all of the trees.

I currently see it queued up for 4.9 and 4.14, don't forget 4.4.

Sorry for the breakage,
Nathan

> 
> thanks,
> 
> greg k-h