mm: ksize() should silently accept a NULL pointer (fa9ba3aa) · Commits · 戴 / test

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:

David Hildenbrand <david@redhat.com> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Link: http://lkml.kernel.org/r/20200616225409.4670-1-william.kucharski@oracle.com Signed-off-by:

mm/slab_common.c

+5 −9

Original line number	Diff line number	Diff line
		@@ -1681,9 +1681,8 @@ 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);

		if (ks >= new_size) {
		@@ -1744,9 +1743,8 @@ void kfree_sensitive(const void *p)
		size_t ks;
		void mem = (void )p;

		if (unlikely(ZERO_OR_NULL_PTR(mem)))
		return;
		ks = ksize(mem);
		if (ks)
		memzero_explicit(mem, ks);
		kfree(mem);
		}
		@@ -1770,8 +1768,6 @@ 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
		@@ -1785,7 +1781,7 @@ 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);