4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Alistair Strachan <astrac...@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 <fwei...@redhat.com>
Reported-by: Carlos O'Donell <car...@redhat.com>
Reported-by: "H. J. Lu" <hjl.to...@gmail.com>
Signed-off-by: Alistair Strachan <astrac...@google.com>
Signed-off-by: Borislav Petkov <b...@suse.de>
Tested-by: Laura Abbott <labb...@redhat.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Carlos O'Donell <car...@redhat.com>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Ingo Molnar <mi...@redhat.com>
Cc: Joel Fernandes <j...@joelfernandes.org>
Cc: kernel-t...@android.com
Cc: Laura Abbott <labb...@redhat.com>
Cc: stable <sta...@vger.kernel.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: X86 ML <x...@kernel.org>
Link: https://lkml.kernel.org/r/20181214223637.35954-1-astrac...@google.com
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
arch/x86/entry/vdso/Makefile | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/entry/vdso/Makefile
+++ b/arch/x86/entry/vdso/Makefile
@@ -171,7 +171,8 @@ quiet_cmd_vdso = VDSO $@
sh $(srctree)/$(src)/checkundef.sh '$(NM)' '$@'
VDSO_LDFLAGS = -shared $(call ld-option, --hash-style=both) \
- $(call ld-option, --build-id) -Bsymbolic
+ $(call ld-option, --build-id) $(call ld-option, --eh-frame-hdr) \
+ -Bsymbolic
GCOV_PROFILE := n
#
