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-rw-r--r--mm/slab_common.c26
1 files changed, 10 insertions, 16 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 3e49bb830060..1cba98acc486 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1348,11 +1348,11 @@ __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;
@@ -1420,21 +1420,21 @@ 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);
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().
@@ -1448,13 +1448,7 @@ 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);