[PATCH v2 11/17] hw/block/nvme: harden cmb access

[Klaus Jensen <its@irrelevant.dk>]

From: Klaus Jensen <k.jensen@samsung.com>

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>
---
 hw/block/nvme.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 7e6cbd3f1058..a440f6617f70 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;
     }
-- 
2.28.0