1 files changed, 34 insertions, 1 deletions
diff --git a/mm/kasan/report_hw_tags.c b/mm/kasan/report_hw_tags.c
index f3d3be614e4b..32e80f78de7d 100644
--- a/mm/kasan/report_hw_tags.c
+++ b/mm/kasan/report_hw_tags.c
@@ -17,10 +17,43 @@
 
 void *kasan_find_first_bad_addr(void *addr, size_t size)
 {
-	/* Return the same value regardless of whether addr_has_metadata(). */
+	/*
+	 * Hardware Tag-Based KASAN only calls this function for normal memory
+	 * accesses, and thus addr points precisely to the first bad address
+	 * with an invalid (and present) memory tag. Therefore:
+	 * 1. Return the address as is without walking memory tags.
+	 * 2. Skip the addr_has_metadata check.
+	 */
 	return kasan_reset_tag(addr);
 }
 
+size_t kasan_get_alloc_size(void *object, struct kmem_cache *cache)
+{
+	size_t size = 0;
+	int i = 0;
+	u8 memory_tag;
+
+	/*
+	 * Skip the addr_has_metadata check, as this function only operates on
+	 * slab memory, which must have metadata.
+	 */
+
+	/*
+	 * The loop below returns 0 for freed objects, for which KASAN cannot
+	 * calculate the allocation size based on the metadata.
+	 */
+	while (size < cache->object_size) {
+		memory_tag = hw_get_mem_tag(object + i * KASAN_GRANULE_SIZE);
+		if (memory_tag != KASAN_TAG_INVALID)
+			size += KASAN_GRANULE_SIZE;
+		else
+			return size;
+		i++;
+	}
+
+	return cache->object_size;
+}
+
 void kasan_metadata_fetch_row(char *buffer, void *row)
 {
 	int i;