Messages in this thread Patch in this message | | | Date | Fri, 27 Mar 2020 17:27:24 -0000 | From | "tip-bot2 for H.J. Lu" <> | Subject | [tip: x86/build] vmlinux.lds: Discard .note.gnu.property sections in generic NOTES |
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The following commit has been merged into the x86/build branch of tip:
Commit-ID: 72cb2113c1bbd82cf3e062a39ff2753ee9d3fae7 Gitweb: https://git.kernel.org/tip/72cb2113c1bbd82cf3e062a39ff2753ee9d3fae7 Author: H.J. Lu <hjl.tools@gmail.com> AuthorDate: Fri, 27 Mar 2020 05:11:01 -07:00 Committer: Borislav Petkov <bp@suse.de> CommitterDate: Fri, 27 Mar 2020 15:58:13 +01:00
vmlinux.lds: Discard .note.gnu.property sections in generic NOTES
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 the kernel linker script only contains a single NOTE segment:
PHDRS { text PT_LOAD FLAGS(5); data PT_LOAD FLAGS(6); percpu PT_LOAD FLAGS(6); init PT_LOAD FLAGS(7); note PT_NOTE FLAGS(0); } SECTIONS { ... .notes : AT(ADDR(.notes) - 0xffffffff80000000) { __start_notes = .; KEEP(*(.not e.*)) __stop_notes = .; } :text :note ... }
The NOTE segment generated by the kernel linker script is aligned to 4 bytes. But .note.gnu.property section must be aligned to 8 bytes on x86-64, resulting in:
[hjl@gnu-skx-1 linux]$ readelf -n vmlinux
Displaying notes found in: .notes Owner Data size Description Xen 0x00000006 Unknown note type: (0x00000006) description data: 6c 69 6e 75 78 00 Xen 0x00000004 Unknown note type: (0x00000007) description data: 32 2e 36 00 xen-3.0 0x00000005 Unknown note type: (0x006e6558) description data: 08 00 00 00 03 readelf: Warning: note with invalid namesz and/or descsz found at offset 0x50 readelf: Warning: type: 0xffffffff, namesize: 0x006e6558, descsize: 0x80000000, alignment: 8
Since note.gnu.property section in the kernel image is never used, discard it.
[ 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/20200327121101.948934-1-hjl.tools@gmail.com --- include/asm-generic/vmlinux.lds.h | 7 +++++++ 1 file changed, 7 insertions(+)
diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h index 2444336..998eafa 100644 --- a/include/asm-generic/vmlinux.lds.h +++ b/include/asm-generic/vmlinux.lds.h @@ -818,7 +818,14 @@ #define TRACEDATA #endif +/* + * Discard .note.gnu.property sections which are unused and have + * different alignment requirement from kernel note sections. + */ #define NOTES \ + /DISCARD/ : { \ + *(.note.gnu.property) \ + } \ .notes : AT(ADDR(.notes) - LOAD_OFFSET) { \ __start_notes = .; \ KEEP(*(.note.*)) \
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