1 files changed, 10 insertions, 16 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 33b1886b06eb..7e96abf1bd7d 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1333,11 +1333,11 @@ __do_krealloc(const void *p, size_t new_size, gfp_t flags)
 	void *ret;
 	size_t ks;
 
-	/* Don't use instrumented ksize to allow precise KASAN poisoning. */
+	/* Check for double-free before calling ksize. */
 	if (likely(!ZERO_OR_NULL_PTR(p))) {
 		if (!kasan_check_byte(p))
 			return NULL;
-		ks = kfence_ksize(p) ?: __ksize(p);
+		ks = ksize(p);
 	} else
 		ks = 0;
 
@@ -1405,8 +1405,10 @@ void kfree_sensitive(const void *p)
 	void *mem = (void *)p;
 
 	ks = ksize(mem);
-	if (ks)
+	if (ks) {
+		kasan_unpoison_range(mem, ks);
 		memzero_explicit(mem, ks);
+	}
 	kfree(mem);
 }
 EXPORT_SYMBOL(kfree_sensitive);
@@ -1427,13 +1429,11 @@ EXPORT_SYMBOL(kfree_sensitive);
  */
 size_t ksize(const void *objp)
 {
-	size_t size;
-
 	/*
-	 * We need to first check that the pointer to the object is valid, and
-	 * only then unpoison the memory. The report printed from ksize() is
-	 * more useful, then when it's printed later when the behaviour could
-	 * be undefined due to a potential use-after-free or double-free.
+	 * We need to first check that the pointer to the object is valid.
+	 * The KASAN report printed from ksize() is more useful, then when
+	 * it's printed later when the behaviour could be undefined due to
+	 * a potential use-after-free or double-free.
 	 *
 	 * We use kasan_check_byte(), which is supported for the hardware
 	 * tag-based KASAN mode, unlike kasan_check_read/write().
@@ -1447,13 +1447,7 @@ size_t ksize(const void *objp)
 	if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
 		return 0;
 
-	size = kfence_ksize(objp) ?: __ksize(objp);
-	/*
-	 * We assume that ksize callers could use whole allocated area,
-	 * so we need to unpoison this area.
-	 */
-	kasan_unpoison_range(objp, size);
-	return size;
+	return kfence_ksize(objp) ?: __ksize(objp);
 }
 EXPORT_SYMBOL(ksize);