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H A Dvdso-layout.lds.Sdiff 4caffe6a28d3157c11cae923a40456a053c520ea Thu Mar 26 18:43:14 CET 2020 H.J. Lu <hjl.tools@gmail.com> x86/vdso: Discard .note.gnu.property sections in vDSO

With the command-line option -mx86-used-note=yes which can also be
enabled at binutils build time with:

--enable-x86-used-note generate GNU x86 used ISA and feature properties

the x86 assembler in binutils 2.32 and above generates a program property
note in a note section, .note.gnu.property, to encode used x86 ISAs and
features. But kernel linker script only contains a single NOTE segment:

PHDRS
{
text PT_LOAD FLAGS(5) FILEHDR PHDRS; /* PF_R|PF_X */
dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
note PT_NOTE FLAGS(4); /* PF_R */
eh_frame_hdr 0x6474e550;
}

The NOTE segment generated by the vDSO linker script is aligned to 4 bytes.
But the .note.gnu.property section must be aligned to 8 bytes on x86-64:

[hjl@gnu-skx-1 vdso]$ readelf -n vdso64.so

Displaying notes found in: .note
Owner Data size Description
Linux 0x00000004 Unknown note type: (0x00000000)
description data: 06 00 00 00
readelf: Warning: note with invalid namesz and/or descsz found at offset 0x20
readelf: Warning: type: 0x78, namesize: 0x00000100, descsize: 0x756e694c, alignment: 8

Since the note.gnu.property section in the vDSO is not checked by the
dynamic linker, discard the .note.gnu.property sections in the vDSO.

[ bp: Massage. ]

Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Kees Cook <keescook@chromium.org>
Link: https://lkml.kernel.org/r/20200326174314.254662-1-hjl.tools@gmail.com