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-rw-r--r--mm/kmemleak.c124
1 files changed, 70 insertions, 54 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index ce79d91..002adc3 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -93,6 +93,7 @@
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/workqueue.h>
+#include <linux/crc32.h>
#include <asm/sections.h>
#include <asm/processor.h>
@@ -108,7 +109,6 @@
#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
#define SECS_FIRST_SCAN 60 /* delay before the first scan */
#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
-#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */
#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
#define BYTES_PER_POINTER sizeof(void *)
@@ -149,6 +149,8 @@ struct kmemleak_object {
int min_count;
/* the total number of pointers found pointing to this object */
int count;
+ /* checksum for detecting modified objects */
+ u32 checksum;
/* memory ranges to be scanned inside an object (empty for all) */
struct hlist_head area_list;
unsigned long trace[MAX_TRACE];
@@ -164,8 +166,6 @@ struct kmemleak_object {
#define OBJECT_REPORTED (1 << 1)
/* flag set to not scan the object */
#define OBJECT_NO_SCAN (1 << 2)
-/* flag set on newly allocated objects */
-#define OBJECT_NEW (1 << 3)
/* number of bytes to print per line; must be 16 or 32 */
#define HEX_ROW_SIZE 16
@@ -321,11 +321,6 @@ static bool color_gray(const struct kmemleak_object *object)
object->count >= object->min_count;
}
-static bool color_black(const struct kmemleak_object *object)
-{
- return object->min_count == KMEMLEAK_BLACK;
-}
-
/*
* Objects are considered unreferenced only if their color is white, they have
* not be deleted and have a minimum age to avoid false positives caused by
@@ -333,7 +328,7 @@ static bool color_black(const struct kmemleak_object *object)
*/
static bool unreferenced_object(struct kmemleak_object *object)
{
- return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
+ return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
time_before_eq(object->jiffies + jiffies_min_age,
jiffies_last_scan);
}
@@ -381,6 +376,7 @@ static void dump_object_info(struct kmemleak_object *object)
pr_notice(" min_count = %d\n", object->min_count);
pr_notice(" count = %d\n", object->count);
pr_notice(" flags = 0x%lx\n", object->flags);
+ pr_notice(" checksum = %d\n", object->checksum);
pr_notice(" backtrace:\n");
print_stack_trace(&trace, 4);
}
@@ -522,12 +518,13 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
INIT_HLIST_HEAD(&object->area_list);
spin_lock_init(&object->lock);
atomic_set(&object->use_count, 1);
- object->flags = OBJECT_ALLOCATED | OBJECT_NEW;
+ object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
object->size = size;
object->min_count = min_count;
- object->count = -1; /* no color initially */
+ object->count = 0; /* white color initially */
object->jiffies = jiffies;
+ object->checksum = 0;
/* task information */
if (in_irq()) {
@@ -949,6 +946,20 @@ void __ref kmemleak_no_scan(const void *ptr)
EXPORT_SYMBOL(kmemleak_no_scan);
/*
+ * Update an object's checksum and return true if it was modified.
+ */
+static bool update_checksum(struct kmemleak_object *object)
+{
+ u32 old_csum = object->checksum;
+
+ if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
+ return false;
+
+ object->checksum = crc32(0, (void *)object->pointer, object->size);
+ return object->checksum != old_csum;
+}
+
+/*
* Memory scanning is a long process and it needs to be interruptable. This
* function checks whether such interrupt condition occured.
*/
@@ -1082,6 +1093,39 @@ out:
}
/*
+ * Scan the objects already referenced (gray objects). More objects will be
+ * referenced and, if there are no memory leaks, all the objects are scanned.
+ */
+static void scan_gray_list(void)
+{
+ struct kmemleak_object *object, *tmp;
+
+ /*
+ * The list traversal is safe for both tail additions and removals
+ * from inside the loop. The kmemleak objects cannot be freed from
+ * outside the loop because their use_count was incremented.
+ */
+ object = list_entry(gray_list.next, typeof(*object), gray_list);
+ while (&object->gray_list != &gray_list) {
+ cond_resched();
+
+ /* may add new objects to the list */
+ if (!scan_should_stop())
+ scan_object(object);
+
+ tmp = list_entry(object->gray_list.next, typeof(*object),
+ gray_list);
+
+ /* remove the object from the list and release it */
+ list_del(&object->gray_list);
+ put_object(object);
+
+ object = tmp;
+ }
+ WARN_ON(!list_empty(&gray_list));
+}
+
+/*
* Scan data sections and all the referenced memory blocks allocated via the
* kernel's standard allocators. This function must be called with the
* scan_mutex held.
@@ -1089,10 +1133,9 @@ out:
static void kmemleak_scan(void)
{
unsigned long flags;
- struct kmemleak_object *object, *tmp;
+ struct kmemleak_object *object;
int i;
int new_leaks = 0;
- int gray_list_pass = 0;
jiffies_last_scan = jiffies;
@@ -1113,7 +1156,6 @@ static void kmemleak_scan(void)
#endif
/* reset the reference count (whiten the object) */
object->count = 0;
- object->flags &= ~OBJECT_NEW;
if (color_gray(object) && get_object(object))
list_add_tail(&object->gray_list, &gray_list);
@@ -1171,62 +1213,36 @@ static void kmemleak_scan(void)
/*
* Scan the objects already referenced from the sections scanned
- * above. More objects will be referenced and, if there are no memory
- * leaks, all the objects will be scanned. The list traversal is safe
- * for both tail additions and removals from inside the loop. The
- * kmemleak objects cannot be freed from outside the loop because their
- * use_count was increased.
+ * above.
*/
-repeat:
- object = list_entry(gray_list.next, typeof(*object), gray_list);
- while (&object->gray_list != &gray_list) {
- cond_resched();
-
- /* may add new objects to the list */
- if (!scan_should_stop())
- scan_object(object);
-
- tmp = list_entry(object->gray_list.next, typeof(*object),
- gray_list);
-
- /* remove the object from the list and release it */
- list_del(&object->gray_list);
- put_object(object);
-
- object = tmp;
- }
-
- if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES)
- goto scan_end;
+ scan_gray_list();
/*
- * Check for new objects allocated during this scanning and add them
- * to the gray list.
+ * Check for new or unreferenced objects modified since the previous
+ * scan and color them gray until the next scan.
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
- if ((object->flags & OBJECT_NEW) && !color_black(object) &&
- get_object(object)) {
- object->flags &= ~OBJECT_NEW;
+ if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
+ && update_checksum(object) && get_object(object)) {
+ /* color it gray temporarily */
+ object->count = object->min_count;
list_add_tail(&object->gray_list, &gray_list);
}
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
- if (!list_empty(&gray_list))
- goto repeat;
-
-scan_end:
- WARN_ON(!list_empty(&gray_list));
+ /*
+ * Re-scan the gray list for modified unreferenced objects.
+ */
+ scan_gray_list();
/*
- * If scanning was stopped or new objects were being allocated at a
- * higher rate than gray list scanning, do not report any new
- * unreferenced objects.
+ * If scanning was stopped do not report any new unreferenced objects.
*/
- if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES)
+ if (scan_should_stop())
return;
/*
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