ptr_ring: try vmalloc() when kmalloc() fails

This patch switch to use kvmalloc_array() for using a vmalloc()
fallback to help in case kmalloc() fails.

Reported-by: syzbot+e4d4f9ddd4295539735d@syzkaller.appspotmail.com
Fixes: 2e0ab8ca ("ptr_ring: array based FIFO for pointers")
Signed-off-by: NJason Wang <jasowang@redhat.com>
Acked-by: NMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/ptr_ring.h

@@ -464,11 +464,14 @@ static inline int ptr_ring_consume_batched_bh(struct ptr_ring *r,
 	__PTR_RING_PEEK_CALL_v; \
 })
 
+/* Not all gfp_t flags (besides GFP_KERNEL) are allowed. See
+ * documentation for vmalloc for which of them are legal.
+ */
 static inline void **__ptr_ring_init_queue_alloc(unsigned int size, gfp_t gfp)
 {
 	if (size * sizeof(void *) > KMALLOC_MAX_SIZE)
 		return NULL;
-	return kcalloc(size, sizeof(void *), gfp);
+	return kvmalloc_array(size, sizeof(void *), gfp | __GFP_ZERO);
 }
 
 static inline void __ptr_ring_set_size(struct ptr_ring *r, int size)
@@ -603,7 +606,7 @@ static inline int ptr_ring_resize(struct ptr_ring *r, int size, gfp_t gfp,
 	spin_unlock(&(r)->producer_lock);
 	spin_unlock_irqrestore(&(r)->consumer_lock, flags);
 
-	kfree(old);
+	kvfree(old);
 
 	return 0;
 }
@@ -643,7 +646,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
 	}
 
 	for (i = 0; i < nrings; ++i)
-		kfree(queues[i]);
+		kvfree(queues[i]);
 
 	kfree(queues);
 
@@ -651,7 +654,7 @@ static inline int ptr_ring_resize_multiple(struct ptr_ring **rings,
 
 nomem:
 	while (--i >= 0)
-		kfree(queues[i]);
+		kvfree(queues[i]);
 
 	kfree(queues);
 
@@ -666,7 +669,7 @@ static inline void ptr_ring_cleanup(struct ptr_ring *r, void (*destroy)(void *))
 	if (destroy)
 		while ((ptr = ptr_ring_consume(r)))
 			destroy(ptr);
-	kfree(r->queue);
+	kvfree(r->queue);
 }
 
 #endif /* _LINUX_PTR_RING_H  */