[PATCH 8/8] x86, microcode, intel: defend apply_microcode_intel with BUG_ON

Henrique de Moraes Holschuh
2014-09-08T17:48:28Z

Microcode updates that requires an unknown loader should never reach the
apply_* functions (the code should have rejected it earlier). Likewise
for an unknown microcode header layout.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
---
arch/x86/kernel/cpu/microcode/intel.c | 2 ++
arch/x86/kernel/cpu/microcode/intel_early.c | 2 ++
2 files changed, 4 insertions(+)

diff --git a/arch/x86/kernel/cpu/microcode/intel.c b/arch/x86/kernel/cpu/microcode/intel.c
index 40caef1..439681f 100644
--- a/arch/x86/kernel/cpu/microcode/intel.c
+++ b/arch/x86/kernel/cpu/microcode/intel.c
@@ -157,6 +157,8 @@ static int apply_microcode_intel(int cpu)
if (mc_intel == NULL)
return 0;

+ BUG_ON(mc_intel->hdr.hdrver != 1 || mc_intel->hdr.ldrver != 1);
+
/* Intel SDM vol 3A section 9.11.6, page 9-34 */
if (WARN_ONCE((unsigned long)(mc_intel->bits) % 16,
"microcode data incorrectly aligned"))
diff --git a/arch/x86/kernel/cpu/microcode/intel_early.c b/arch/x86/kernel/cpu/microcode/intel_early.c
index 994c59b..095db11 100644
--- a/arch/x86/kernel/cpu/microcode/intel_early.c
+++ b/arch/x86/kernel/cpu/microcode/intel_early.c
@@ -671,6 +671,8 @@ static int apply_microcode_early(struct mc_saved_data *mc_saved_data,
if (mc_intel == NULL)
return 0;

+ BUG_ON(mc_intel->hdr.hdrver != 1 || mc_intel->hdr.ldrver != 1);
+
mcu_data = mc_intel->bits;
aligned_mcu_data = mc_intel->bits;

--
1.7.10.4