From: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
commit ac49303d9ef0ad98b79867a380ef23480e48870b upstream.
Commit "bpf: Process in-kernel BTF" in linux-next introduced an undefined
__weak symbol, which results in an R_390_GLOB_DAT relocation type. That
is not yet handled by the KASLR relocation code, and the kernel stops with
the message "Unknown relocation type".
Add code to detect and handle R_390_GLOB_DAT relocation types and undefined
symbols.
Fixes: 805bc0bc238f ("s390/kernel: build a relocatable kernel")
Cc: <stable@xxxxxxxxxxxxxxx> # v5.2+
Acked-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/boot/startup.c | 14 +++++++++++---
arch/s390/kernel/machine_kexec_reloc.c | 1 +
2 files changed, 12 insertions(+), 3 deletions(-)
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -101,10 +101,18 @@ static void handle_relocs(unsigned long
dynsym = (Elf64_Sym *) vmlinux.dynsym_start;
for (rela = rela_start; rela < rela_end; rela++) {
loc = rela->r_offset + offset;
- val = rela->r_addend + offset;
+ val = rela->r_addend;
r_sym = ELF64_R_SYM(rela->r_info);
- if (r_sym)
- val += dynsym[r_sym].st_value;
+ if (r_sym) {
+ if (dynsym[r_sym].st_shndx != SHN_UNDEF)
+ val += dynsym[r_sym].st_value + offset;
+ } else {
+ /*
+ * 0 == undefined symbol table index (STN_UNDEF),
+ * used for R_390_RELATIVE, only add KASLR offset
+ */
+ val += offset;
+ }
r_type = ELF64_R_TYPE(rela->r_info);
rc = arch_kexec_do_relocs(r_type, (void *) loc, val, 0);
if (rc)
--- a/arch/s390/kernel/machine_kexec_reloc.c
+++ b/arch/s390/kernel/machine_kexec_reloc.c
@@ -27,6 +27,7 @@ int arch_kexec_do_relocs(int r_type, voi
*(u32 *)loc = val;
break;
case R_390_64: /* Direct 64 bit. */
+ case R_390_GLOB_DAT:
*(u64 *)loc = val;
break;
case R_390_PC16: /* PC relative 16 bit. */
