[PATCH 5/6] notifiers: Use CHECK_DATA_CORRUPTION() on checks

[Kees Cook]

When performing notifier function pointer sanity checking, allow
CONFIG_BUG_ON_DATA_CORRUPTION to upgrade from a WARN to a BUG.
Additionally enables CONFIG_DEBUG_NOTIFIERS when selecting
CONFIG_BUG_ON_DATA_CORRUPTION.

Signed-off-by: Kees Cook <keesc...@chromium.org>
---
 kernel/notifier.c | 5 +++--
 lib/Kconfig.debug | 3 ++-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/notifier.c b/kernel/notifier.c
index 6196af8a8223..58cc14958d92 100644
--- a/kernel/notifier.c
+++ b/kernel/notifier.c
@@ -84,8 +84,9 @@ static int notifier_call_chain(struct notifier_block **nl,
                next_nb = rcu_dereference_raw(nb->next);
 
 #ifdef CONFIG_DEBUG_NOTIFIERS
-               if (unlikely(!func_ptr_is_kernel_text(nb->notifier_call))) {
-                       WARN(1, "Invalid notifier called!");
+               if (CHECK_DATA_CORRUPTION(
+                               !func_ptr_is_kernel_text(nb->notifier_call),
+                               "Invalid notifier called!")) {
                        nb = next_nb;
                        continue;
                }
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 42c61cfe7d19..70e9f2c1bb30 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1277,7 +1277,7 @@ config DEBUG_SG
 
 config DEBUG_NOTIFIERS
        bool "Debug notifier call chains"
-       depends on DEBUG_KERNEL
+       depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
        help
          Enable this to turn on sanity checking for notifier call chains.
          This is most useful for kernel developers to make sure that
@@ -1995,6 +1995,7 @@ config BUG_ON_DATA_CORRUPTION
        bool "Trigger a BUG when data corruption is detected"
        select DEBUG_CREDENTIALS
        select DEBUG_LIST
+       select DEBUG_NOTIFIERS
        select DEBUG_SG
        help
          This option enables several inexpensive data corruption checks.
-- 
2.7.4