x86: harden kernel code patching

Signed-off-by: Ingo Molnar <mingo@elte.hu>

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index 60299f61843fc9c13a701704edff8567baf3e08e..65c7857a90ddfc6ff084c6817baba045ced0ad71 100644 (file)
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -519,6 +519,7 @@ void *__kprobes text_poke(void *addr, const void *opcode, size_t len)
                pages[1] = vmalloc_to_page(addr + PAGE_SIZE);
        } else {
                pages[0] = virt_to_page(addr);
+               WARN_ON(!PageReserved(pages[0]));
                pages[1] = virt_to_page(addr + PAGE_SIZE);
        }
        BUG_ON(!pages[0]);