[RFC,08/10] kfence, lockdep: make KFENCE compatible with lockdep

Commit Message

Marco Elver Sept. 7, 2020, 1:40 p.m. UTC

Lockdep checks that dynamic key registration is only performed on keys
that are not static objects. With KFENCE, it is possible that such a
dynamically allocated key is a KFENCE object which may, however, be
allocated from a static memory pool (if HAVE_ARCH_KFENCE_STATIC_POOL).

Therefore, ignore KFENCE-allocated objects in static_obj().

Co-developed-by: Alexander Potapenko <[e-mail]>
Signed-off-by: Alexander Potapenko <[e-mail]>
Signed-off-by: Marco Elver <[e-mail]>
---
 kernel/locking/lockdep.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Patch

diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index 54b74fabf40c..0cf5d5ecbd31 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -38,6 +38,7 @@ 
 #include <linux/seq_file.h>
 #include <linux/spinlock.h>
 #include <linux/kallsyms.h>
+#include <linux/kfence.h>
 #include <linux/interrupt.h>
 #include <linux/stacktrace.h>
 #include <linux/debug_locks.h>
@@ -755,6 +756,13 @@  static int static_obj(const void *obj)
 	if (arch_is_kernel_initmem_freed(addr))
 		return 0;
 
+	/*
+	 * KFENCE objects may be allocated from a static memory pool, but are
+	 * not actually static objects.
+	 */
+	if (is_kfence_address(obj))
+		return 0;
+
 	/*
 	 * static variable?
 	 */