pcie_sriov: Validate NumVFs

The guest may write NumVFs greater than TotalVFs and that can lead
to buffer overflow in VF implementations.

Cc: qemu-stable@nongnu.org
Fixes: CVE-2024-26327
Fixes: 7c0fa8d ("pcie: Add support for Single Root I/O Virtualization (SR/IOV)")
Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-Id: <20240228-reuse-v8-2-282660281e60@daynix.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Sriram Yagnaraman <sriram.yagnaraman@ericsson.com>
(cherry picked from commit 6081b42)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/pci/pcie_sriov.c

@@ -176,6 +176,9 @@ static void register_vfs(PCIDevice *dev)
 
     assert(sriov_cap > 0);
     num_vfs = pci_get_word(dev->config + sriov_cap + PCI_SRIOV_NUM_VF);
+    if (num_vfs > pci_get_word(dev->config + sriov_cap + PCI_SRIOV_TOTAL_VF)) {
+        return;
+    }
 
     dev->exp.sriov_pf.vf = g_new(PCIDevice *, num_vfs);