From cad9aa6fbdccd95e56e10cfa57c354a20a333717 Mon Sep 17 00:00:00 2001 From: Akihiko Odaki Date: Sun, 27 Jul 2025 15:50:08 +0900 Subject: [PATCH] pcie_sriov: Fix configuration and state synchronization Fix issues in PCIe SR-IOV configuration register handling that caused inconsistent internal state due to improper write mask handling and incorrect migration behavior. Two main problems were identified: 1. VF Enable bit write mask handling: pcie_sriov_config_write() incorrectly assumed that its val parameter was already masked, causing it to ignore the actual write mask. This led to the VF Enable bit being processed even when masked, resulting in incorrect VF registration/unregistration. It is identified as CVE-2025-54567. 2. Migration state inconsistency: pcie_sriov_pf_post_load() unconditionally called register_vfs() regardless of the VF Enable bit state, creating inconsistent internal state when VFs should not be enabled. Additionally, it failed to properly update the NumVFs write mask based on the current configuration. It is identified as CVE-2025-54566. Root cause analysis revealed that both functions relied on incorrect special-case assumptions instead of properly reading and consuming the actual configuration values. This change introduces a unified consume_config() function that reads actual configuration values and synchronize the internal state without special-case assumptions. The solution only adds register read overhead in non-hot-path code while ensuring correct SR-IOV state management across configuration writes and migration scenarios. Fixes: 5e7dd17e4348 ("pcie_sriov: Remove num_vfs from PCIESriovPF") Fixes: f9efcd47110d ("pcie_sriov: Register VFs after migration") Fixes: CVE-2025-54566 Fixes: CVE-2025-54567 Cc: qemu-stable@nongnu.org Reported-by: Corentin BAYET Signed-off-by: Akihiko Odaki Message-Id: <20250727-wmask-v2-1-394910b1c0b6@rsg.ci.i.u-tokyo.ac.jp> Reviewed-by: Michael S. Tsirkin Signed-off-by: Michael S. Tsirkin --- hw/pci/pcie_sriov.c | 42 +++++++++++++++++++++++------------------- 1 file changed, 23 insertions(+), 19 deletions(-) diff --git a/hw/pci/pcie_sriov.c b/hw/pci/pcie_sriov.c index 3ad18744f4a..8a4bf0d6f7c 100644 --- a/hw/pci/pcie_sriov.c +++ b/hw/pci/pcie_sriov.c @@ -64,6 +64,27 @@ static void unregister_vfs(PCIDevice *dev) pci_set_word(dev->wmask + dev->exp.sriov_cap + PCI_SRIOV_NUM_VF, 0xffff); } +static void consume_config(PCIDevice *dev) +{ + uint8_t *cfg = dev->config + dev->exp.sriov_cap; + + if (pci_get_word(cfg + PCI_SRIOV_CTRL) & PCI_SRIOV_CTRL_VFE) { + register_vfs(dev); + } else { + uint8_t *wmask = dev->wmask + dev->exp.sriov_cap; + uint16_t num_vfs = pci_get_word(cfg + PCI_SRIOV_NUM_VF); + uint16_t wmask_val = PCI_SRIOV_CTRL_MSE | PCI_SRIOV_CTRL_ARI; + + unregister_vfs(dev); + + if (num_vfs <= pci_get_word(cfg + PCI_SRIOV_TOTAL_VF)) { + wmask_val |= PCI_SRIOV_CTRL_VFE; + } + + pci_set_word(wmask + PCI_SRIOV_CTRL, wmask_val); + } +} + static bool pcie_sriov_pf_init_common(PCIDevice *dev, uint16_t offset, uint16_t vf_dev_id, uint16_t init_vfs, uint16_t total_vfs, uint16_t vf_offset, @@ -416,30 +437,13 @@ void pcie_sriov_config_write(PCIDevice *dev, uint32_t address, trace_sriov_config_write(dev->name, PCI_SLOT(dev->devfn), PCI_FUNC(dev->devfn), off, val, len); - if (range_covers_byte(off, len, PCI_SRIOV_CTRL)) { - if (val & PCI_SRIOV_CTRL_VFE) { - register_vfs(dev); - } else { - unregister_vfs(dev); - } - } else if (range_covers_byte(off, len, PCI_SRIOV_NUM_VF)) { - uint8_t *cfg = dev->config + sriov_cap; - uint8_t *wmask = dev->wmask + sriov_cap; - uint16_t num_vfs = pci_get_word(cfg + PCI_SRIOV_NUM_VF); - uint16_t wmask_val = PCI_SRIOV_CTRL_MSE | PCI_SRIOV_CTRL_ARI; - - if (num_vfs <= pci_get_word(cfg + PCI_SRIOV_TOTAL_VF)) { - wmask_val |= PCI_SRIOV_CTRL_VFE; - } - - pci_set_word(wmask + PCI_SRIOV_CTRL, wmask_val); - } + consume_config(dev); } void pcie_sriov_pf_post_load(PCIDevice *dev) { if (dev->exp.sriov_cap) { - register_vfs(dev); + consume_config(dev); } } -- 2.47.2