x86, alternatives: BUG on encountering an invalid CPU feature number

Make the alternatives-patching code BUG on encountering an invalid CPU
feature number.  Should have done this a long time ago.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Yinghai Lu <yinhai@kernel.org>
Cc: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <tip-df378ccfc4dd04e263426ad805516915874774aa@git.kernel.org>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 70237732a6c7..f65ab8b014c4 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -214,6 +214,7 @@ void __init_or_module apply_alternatives(struct alt_instr *start,
                 u8 *instr = a->instr;
                 BUG_ON(a->replacementlen > a->instrlen);
                 BUG_ON(a->instrlen > sizeof(insnbuf));
+                BUG_ON(a->cpuid >= NCAPINTS*32);
                 if (!boot_cpu_has(a->cpuid))
                         continue;
 #ifdef CONFIG_X86_64