From baa763b565386b1383b87b6fb76e72db84a0ff16 Mon Sep 17 00:00:00 2001
From: Suzuki K Poulose <suzuki.poulose@arm.com>
Date: Fri, 9 Sep 2016 14:07:11 +0100
Subject: [PATCH] arm64: alternative: Disallow patching instructions using
literals
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 <marc.zyngier@arm.com>
Cc: Andre Przywara <andre.przywara@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Suggested-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
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 4434dabde898b..992918dfbe2db 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;
--
2.30.2