[PATCH] mm: ksize() should silently accept a NULL pointer

[William Kucharski]

Other mm routines such as kfree() and kzfree() silently do the right
thing if passed a NULL pointer, so ksize() should do the same.

Signed-off-by: William Kucharski <william.kuchar...@oracle.com>
---
 mm/slab_common.c | 14 +++++---------
 1 file changed, 5 insertions(+), 9 deletions(-)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 9e72ba224175..2bff01ad94d8 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -1660,10 +1660,9 @@ static __always_inline void *__do_krealloc(const void 
*p, size_t new_size,
                                           gfp_t flags)
 {
        void *ret;
-       size_t ks = 0;
+       size_t ks;
 
-       if (p)
-               ks = ksize(p);
+       ks = ksize(p);
 
        if (ks >= new_size) {
                p = kasan_krealloc((void *)p, new_size, flags);
@@ -1723,10 +1722,9 @@ void kzfree(const void *p)
        size_t ks;
        void *mem = (void *)p;
 
-       if (unlikely(ZERO_OR_NULL_PTR(mem)))
-               return;
        ks = ksize(mem);
-       memset(mem, 0, ks);
+       if (ks)
+               memset(mem, 0, ks);
        kfree(mem);
 }
 EXPORT_SYMBOL(kzfree);
@@ -1749,8 +1747,6 @@ size_t ksize(const void *objp)
 {
        size_t size;
 
-       if (WARN_ON_ONCE(!objp))
-               return 0;
        /*
         * We need to check that the pointed to object is valid, and only then
         * unpoison the shadow memory below. We use __kasan_check_read(), to
@@ -1764,7 +1760,7 @@ size_t ksize(const void *objp)
         * We want to perform the check before __ksize(), to avoid potentially
         * crashing in __ksize() due to accessing invalid metadata.
         */
-       if (unlikely(objp == ZERO_SIZE_PTR) || !__kasan_check_read(objp, 1))
+       if (unlikely(ZERO_OR_NULL_PTR(objp)) || !__kasan_check_read(objp, 1))
                return 0;
 
        size = __ksize(objp);
-- 
2.26.2