diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 09d7c902597abe6adcb18f6e7ff1106f5db1b220..d0226e7fdcd029e8b758668393e79f394da054db 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -1175,6 +1175,10 @@ static void nvme_cmb_write(void *opaque, hwaddr addr, uint64_t data,
     unsigned size)
 {
     NvmeCtrl *n = (NvmeCtrl *)opaque;
+
+    if (addr + size > NVME_CMBSZ_GETSIZE(n->bar.cmbsz)) {
+        return;
+    }
     memcpy(&n->cmbuf[addr], &data, size);
 }
 
@@ -1183,6 +1187,9 @@ static uint64_t nvme_cmb_read(void *opaque, hwaddr addr, unsigned size)
     uint64_t val;
     NvmeCtrl *n = (NvmeCtrl *)opaque;
 
+    if (addr + size > NVME_CMBSZ_GETSIZE(n->bar.cmbsz)) {
+        return 0;
+    }
     memcpy(&val, &n->cmbuf[addr], size);
     return val;
 }