hw/block/nvme: harden cmb access

Since the controller has only supported PRPs so far it has not been
required to check the ending address (addr + len - 1) of the CMB access
for validity since it has been guaranteed to be in range of the CMB.

This changes when the controller adds support for SGLs (next patch), so
add that check.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>

1 files changed, 6 insertions, 1 deletions

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 0e916d48d7..c0f1f8ccd4 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -142,7 +142,12 @@ static inline void *nvme_addr_to_cmb(NvmeCtrl *n, hwaddr addr)
 
 static int nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf, int size)
 {
-    if (n->bar.cmbsz && nvme_addr_is_cmb(n, addr)) {
+    hwaddr hi = addr + size - 1;
+    if (hi < addr) {
+        return 1;
+    }
+
+    if (n->bar.cmbsz && nvme_addr_is_cmb(n, addr) && nvme_addr_is_cmb(n, hi)) {
         memcpy(buf, nvme_addr_to_cmb(n, addr), size);
         return 0;
     }