| Message ID | 20240227175746.it.649-kees@kernel.org (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | aaa8736370db1a78f0e8434344a484f9fd20be3b |
| Headers | show |
| Series | [v2] x86, relocs: Ignore relocations in .notes section | expand |
diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index a3bae2b24626..b029fb81ebee 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -653,6 +653,14 @@ static void print_absolute_relocs(void) if (!(sec_applies->shdr.sh_flags & SHF_ALLOC)) { continue; } + /* + * Do not perform relocations in .notes section; any + * values there are meant for pre-boot consumption (e.g. + * startup_xen). + */ + if (sec_applies->shdr.sh_type == SHT_NOTE) { + continue; + } sh_symtab = sec_symtab->symtab; sym_strtab = sec_symtab->link->strtab; for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Rel); j++) {
When building with CONFIG_XEN_PV=y, .text symbols are emitted into the .notes section so that Xen can find the "startup_xen" entry point. This information is used prior to booting the kernel, so relocations are not useful. In fact, performing relocations against the .notes section means that the KASLR base is exposed since /sys/kernel/notes is world-readable. To avoid leaking the KASLR base without breaking unprivileged tools that are expecting to read /sys/kernel/notes, skip performing relocations in the .notes section. The values readable in .notes are then identical to those found in System.map. Reported-by: Guixiong Wei <guixiongwei@gmail.com> Closes: https://lore.kernel.org/all/20240218073501.54555-1-guixiongwei@gmail.com/ Fixes: 5ead97c84fa7 ("xen: Core Xen implementation") Fixes: da1a679cde9b ("Add /sys/kernel/notes") Reviewed-by: Juergen Gross <jgross@suse.com> Signed-off-by: Kees Cook <keescook@chromium.org> --- Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: Borislav Petkov <bp@alien8.de> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: x86@kernel.org Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Tony Luck <tony.luck@intel.com> Cc: Kristen Carlson Accardi <kristen@linux.intel.com> v2: switch to a SHT_NOTE check (jgross) v1: https://lore.kernel.org/all/20240222171840.work.027-kees@kernel.org/ --- arch/x86/tools/relocs.c | 8 ++++++++ 1 file changed, 8 insertions(+)