Fix overflow tests such that we can allocate arrays with zero items.

Linux allows this sillyness and it is needed to make X work on the
integrated graphics on the AMD Ryzen 3 PRO 2200GE APU.

ok jsg@

2 files changed, 3 insertions, 3 deletions

diff --git a/sys/dev/pci/drm/include/linux/mm.h b/sys/dev/pci/drm/include/linux/mm.h
index 2723690beec..da4080289ba 100644
--- a/sys/dev/pci/drm/include/linux/mm.h
+++ b/sys/dev/pci/drm/include/linux/mm.h
@@ -41,7 +41,7 @@ kvmalloc(size_t size, gfp_t flags)
 static inline void *
 kvmalloc_array(size_t n, size_t size, int flags)
 {
-	if (n == 0 || SIZE_MAX / n < size)
+	if (n != 0 && SIZE_MAX / n < size)
 		return NULL;
 	return malloc(n * size, M_DRM, flags);
 }
diff --git a/sys/dev/pci/drm/include/linux/slab.h b/sys/dev/pci/drm/include/linux/slab.h
index b0b65b71a93..0d5463ecc1b 100644
--- a/sys/dev/pci/drm/include/linux/slab.h
+++ b/sys/dev/pci/drm/include/linux/slab.h
@@ -19,7 +19,7 @@ kmalloc(size_t size, int flags)
 static inline void *
 kmalloc_array(size_t n, size_t size, int flags)
 {
-	if (n == 0 || SIZE_MAX / n < size)
+	if (n != 0 && SIZE_MAX / n < size)
 		return NULL;
 	return malloc(n * size, M_DRM, flags);
 }
@@ -27,7 +27,7 @@ kmalloc_array(size_t n, size_t size, int flags)
 static inline void *
 kcalloc(size_t n, size_t size, int flags)
 {
-	if (n == 0 || SIZE_MAX / n < size)
+	if (n != 0 && SIZE_MAX / n < size)
 		return NULL;
 	return malloc(n * size, M_DRM, flags | M_ZERO);
 }