4.18-stable review patch. If anyone has any objections, please let me know.
------------------
From: Nicholas Piggin npiggin@gmail.com
[ Upstream commit b851ba02a6f3075f0f99c60c4bc30a4af80cf428 ]
The recent module relocation overflow crash demonstrated that we have no range checking on REL32 relative relocations. This patch implements a basic check, the same kernel that previously oopsed and rebooted now continues with some of these errors when loading the module:
module_64: x_tables: REL32 527703503449812 out of range!
Possibly other relocations (ADDR32, REL16, TOC16, etc.) should also have overflow checks.
Signed-off-by: Nicholas Piggin npiggin@gmail.com Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/powerpc/kernel/module_64.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
--- a/arch/powerpc/kernel/module_64.c +++ b/arch/powerpc/kernel/module_64.c @@ -685,7 +685,14 @@ int apply_relocate_add(Elf64_Shdr *sechd
case R_PPC64_REL32: /* 32 bits relative (used by relative exception tables) */ - *(u32 *)location = value - (unsigned long)location; + /* Convert value to relative */ + value -= (unsigned long)location; + if (value + 0x80000000 > 0xffffffff) { + pr_err("%s: REL32 %li out of range!\n", + me->name, (long int)value); + return -ENOEXEC; + } + *(u32 *)location = value; break;
case R_PPC64_TOCSAVE: