lkml.org 
[lkml]   [2020]   [Mar]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: x86/build] x86/vdso: Discard .note.gnu.property sections in vDSO
The following commit has been merged into the x86/build branch of tip:

Commit-ID: 4caffe6a28d3157c11cae923a40456a053c520ea
Gitweb: https://git.kernel.org/tip/4caffe6a28d3157c11cae923a40456a053c520ea
Author: H.J. Lu <hjl.tools@gmail.com>
AuthorDate: Thu, 26 Mar 2020 10:43:14 -07:00
Committer: Borislav Petkov <bp@suse.de>
CommitterDate: Fri, 27 Mar 2020 15:53:05 +01:00

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
---
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 ea7e015..4d15293 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
\
 
 \ /
  Last update: 2020-03-27 18:27    [W:0.051 / U:3.980 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site