The alternative code patching doesn't check if the replaced instruction uses a pc relative literal. This could cause silent corruption in the instruction stream as the instruction will be executed from a different address than what it was compiled for. Catch all such cases.
Cc: Marc Zyngier <[email protected]> Cc: Andre Przywara <[email protected]> Cc: Mark Rutland <[email protected]> Cc: Catalin Marinas <[email protected]> Suggested-by: Will Deacon <[email protected]> Signed-off-by: Suzuki K Poulose <[email protected]> --- arch/arm64/kernel/alternative.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c index 4434dab..992918d 100644 --- a/arch/arm64/kernel/alternative.c +++ b/arch/arm64/kernel/alternative.c @@ -79,6 +79,12 @@ static u32 get_alt_insn(struct alt_instr *alt, u32 *insnptr, u32 *altinsnptr) offset = target - (unsigned long)insnptr; insn = aarch64_set_branch_offset(insn, offset); } + } else if (aarch64_insn_uses_literal(insn)) { + /* + * Disallow patching unhandled instructions using PC relative + * literal addresses + */ + BUG(); } return insn; -- 2.7.4
