From 4caffe6a28d3157c11cae923a40456a053c520ea Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 26 Mar 2020 10:43:14 -0700 Subject: [PATCH] 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 Signed-off-by: Borislav Petkov Reviewed-by: Kees Cook Link: https://lkml.kernel.org/r/20200326174314.254662-1-hjl.tools@gmail.com --- arch/x86/entry/vdso/vdso-layout.lds.S | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/entry/vdso/vdso-layout.lds.S b/arch/x86/entry/vdso/vdso-layout.lds.S index ea7e0155c604..4d152933547d 100644 --- a/arch/x86/entry/vdso/vdso-layout.lds.S +++ b/arch/x86/entry/vdso/vdso-layout.lds.S @@ -57,6 +57,13 @@ SECTIONS *(.gnu.linkonce.b.*) } :text + /* + * Discard .note.gnu.property sections which are unused and have + * different alignment requirement from vDSO note sections. + */ + /DISCARD/ : { + *(.note.gnu.property) + } .note : { *(.note.*) } :text :note .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr