kasan: improve double-free reports
Currently we just dump stack in case of double free bug.
Let's dump all info about the object that we have.
[aryabinin@virtuozzo.com: change double free message per Alexander]
Link: http://lkml.kernel.org/r/1470153654-30160-1-git-send-email-aryabinin@virtuozzo.com
Link: http://lkml.kernel.org/r/1470062715-14077-6-git-send-email-aryabinin@virtuozzo.com
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index f437398..24c1211 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -116,6 +116,26 @@
sizeof(init_thread_union.stack));
}
+static DEFINE_SPINLOCK(report_lock);
+
+static void kasan_start_report(unsigned long *flags)
+{
+ /*
+ * Make sure we don't end up in loop.
+ */
+ kasan_disable_current();
+ spin_lock_irqsave(&report_lock, *flags);
+ pr_err("==================================================================\n");
+}
+
+static void kasan_end_report(unsigned long *flags)
+{
+ pr_err("==================================================================\n");
+ add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
+ spin_unlock_irqrestore(&report_lock, *flags);
+ kasan_enable_current();
+}
+
static void print_track(struct kasan_track *track)
{
pr_err("PID = %u\n", track->pid);
@@ -129,8 +149,7 @@
}
}
-static void kasan_object_err(struct kmem_cache *cache, struct page *page,
- void *object, char *unused_reason)
+static void kasan_object_err(struct kmem_cache *cache, void *object)
{
struct kasan_alloc_meta *alloc_info = get_alloc_info(cache, object);
@@ -147,6 +166,18 @@
print_track(&alloc_info->free_track);
}
+void kasan_report_double_free(struct kmem_cache *cache, void *object,
+ s8 shadow)
+{
+ unsigned long flags;
+
+ kasan_start_report(&flags);
+ pr_err("BUG: Double free or freeing an invalid pointer\n");
+ pr_err("Unexpected shadow byte: 0x%hhX\n", shadow);
+ kasan_object_err(cache, object);
+ kasan_end_report(&flags);
+}
+
static void print_address_description(struct kasan_access_info *info)
{
const void *addr = info->access_addr;
@@ -160,8 +191,7 @@
struct kmem_cache *cache = page->slab_cache;
object = nearest_obj(cache, page,
(void *)info->access_addr);
- kasan_object_err(cache, page, object,
- "kasan: bad access detected");
+ kasan_object_err(cache, object);
return;
}
dump_page(page, "kasan: bad access detected");
@@ -226,19 +256,13 @@
}
}
-static DEFINE_SPINLOCK(report_lock);
-
static void kasan_report_error(struct kasan_access_info *info)
{
unsigned long flags;
const char *bug_type;
- /*
- * Make sure we don't end up in loop.
- */
- kasan_disable_current();
- spin_lock_irqsave(&report_lock, flags);
- pr_err("==================================================================\n");
+ kasan_start_report(&flags);
+
if (info->access_addr <
kasan_shadow_to_mem((void *)KASAN_SHADOW_START)) {
if ((unsigned long)info->access_addr < PAGE_SIZE)
@@ -259,10 +283,8 @@
print_address_description(info);
print_shadow_for_address(info->first_bad_addr);
}
- pr_err("==================================================================\n");
- add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
- spin_unlock_irqrestore(&report_lock, flags);
- kasan_enable_current();
+
+ kasan_end_report(&flags);
}
void kasan_report(unsigned long addr, size_t size,