Messages in this thread | | | Date | Mon, 22 Jun 2020 15:27:47 -0700 | From | Kees Cook <> | Subject | Re: [PATCH v2 1/3] vmlinux.lds.h: Add .gnu.version* to DISCARDS |
| |
On Mon, Jun 22, 2020 at 03:00:43PM -0700, Fangrui Song wrote: > On 2020-06-22, Kees Cook wrote: > > For vmlinux linking, no architecture uses the .gnu.version* section, > > so remove it via the common DISCARDS macro in preparation for adding > > --orphan-handling=warn more widely. > > > > Signed-off-by: Kees Cook <keescook@chromium.org> > > --- > > include/asm-generic/vmlinux.lds.h | 1 + > > 1 file changed, 1 insertion(+) > > > > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h > > index db600ef218d7..6fbe9ed10cdb 100644 > > --- a/include/asm-generic/vmlinux.lds.h > > +++ b/include/asm-generic/vmlinux.lds.h > > @@ -934,6 +934,7 @@ > > *(.discard) \ > > *(.discard.*) \ > > *(.modinfo) \ > > + *(.gnu.version*) \ > > } > > > > /** > > -- > > 2.25.1 > > I wonder what lead to .gnu.version{,_d,_r} sections in the kernel.
This looks like a bug in bfd.ld? There are no versioned symbols in any of the input files (and no output section either!)
The link command is: $ ld -m elf_x86_64 --no-ld-generated-unwind-info -z noreloc-overflow -pie \ --no-dynamic-linker --orphan-handling=warn -T \ arch/x86/boot/compressed/vmlinux.lds \ arch/x86/boot/compressed/kernel_info.o \ arch/x86/boot/compressed/head_64.o arch/x86/boot/compressed/misc.o \ arch/x86/boot/compressed/string.o arch/x86/boot/compressed/cmdline.o \ arch/x86/boot/compressed/error.o arch/x86/boot/compressed/piggy.o \ arch/x86/boot/compressed/cpuflags.o \ arch/x86/boot/compressed/early_serial_console.o \ arch/x86/boot/compressed/kaslr.o arch/x86/boot/compressed/kaslr_64.o \ arch/x86/boot/compressed/mem_encrypt.o \ arch/x86/boot/compressed/pgtable_64.o arch/x86/boot/compressed/acpi.o \ -o arch/x86/boot/compressed/vmlinux
None of the inputs have the section:
$ for i in arch/x86/boot/compressed/kernel_info.o \ arch/x86/boot/compressed/head_64.o arch/x86/boot/compressed/misc.o \ arch/x86/boot/compressed/string.o arch/x86/boot/compressed/cmdline.o \ arch/x86/boot/compressed/error.o arch/x86/boot/compressed/piggy.o \ arch/x86/boot/compressed/cpuflags.o \ arch/x86/boot/compressed/early_serial_console.o \ arch/x86/boot/compressed/kaslr.o arch/x86/boot/compressed/kaslr_64.o \ arch/x86/boot/compressed/mem_encrypt.o \ arch/x86/boot/compressed/pgtable_64.o arch/x86/boot/compressed/acpi.o \ ; do echo -n $i": "; readelf -Vs $i | grep 'version'; done arch/x86/boot/compressed/kernel_info.o: No version information found in this file. arch/x86/boot/compressed/head_64.o: No version information found in this file. arch/x86/boot/compressed/misc.o: No version information found in this file. arch/x86/boot/compressed/string.o: No version information found in this file. arch/x86/boot/compressed/cmdline.o: No version information found in this file. arch/x86/boot/compressed/error.o: No version information found in this file. arch/x86/boot/compressed/piggy.o: No version information found in this file. arch/x86/boot/compressed/cpuflags.o: No version information found in this file. arch/x86/boot/compressed/early_serial_console.o: No version information found in this file. arch/x86/boot/compressed/kaslr.o: No version information found in this file. arch/x86/boot/compressed/kaslr_64.o: No version information found in this file. arch/x86/boot/compressed/mem_encrypt.o: No version information found in this file. arch/x86/boot/compressed/pgtable_64.o: No version information found in this file. arch/x86/boot/compressed/acpi.o: No version information found in this file.
And it's not in the output:
$ readelf -Vs arch/x86/boot/compressed/vmlinux | grep version No version information found in this file.
So... for the kernel we need to silence it right now.
-- Kees Cook
| |