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Re: [PATCH v6 01/15] hw/nvme: Use pcie_sriov_num_vfs()
From: |
Klaus Jensen |
Subject: |
Re: [PATCH v6 01/15] hw/nvme: Use pcie_sriov_num_vfs() |
Date: |
Tue, 20 Feb 2024 15:47:21 +0100 |
On Feb 20 15:29, Kevin Wolf wrote:
> Am 20.02.2024 um 13:24 hat Akihiko Odaki geschrieben:
> > nvme_sriov_pre_write_ctrl() used to directly inspect SR-IOV
> > configurations to know the number of VFs being disabled due to SR-IOV
> > configuration writes, but the logic was flawed and resulted in
> > out-of-bound memory access.
> >
> > It assumed PCI_SRIOV_NUM_VF always has the number of currently enabled
> > VFs, but it actually doesn't in the following cases:
> > - PCI_SRIOV_NUM_VF has been set but PCI_SRIOV_CTRL_VFE has never been.
> > - PCI_SRIOV_NUM_VF was written after PCI_SRIOV_CTRL_VFE was set.
> > - VFs were only partially enabled because of realization failure.
> >
> > It is a responsibility of pcie_sriov to interpret SR-IOV configurations
> > and pcie_sriov does it correctly, so use pcie_sriov_num_vfs(), which it
> > provides, to get the number of enabled VFs before and after SR-IOV
> > configuration writes.
> >
> > Cc: qemu-stable@nongnu.org
> > Fixes: CVE-2024-26328
> > Fixes: 11871f53ef8e ("hw/nvme: Add support for the Virtualization
> > Management command")
> > Suggested-by: Michael S. Tsirkin <mst@redhat.com>
> > Signed-off-by: Akihiko Odaki <akihiko.odaki@daynix.com>
> > ---
> > hw/nvme/ctrl.c | 26 ++++++++------------------
> > 1 file changed, 8 insertions(+), 18 deletions(-)
> >
> > diff --git a/hw/nvme/ctrl.c b/hw/nvme/ctrl.c
> > index f026245d1e9e..7a56e7b79b4d 100644
> > --- a/hw/nvme/ctrl.c
> > +++ b/hw/nvme/ctrl.c
> > @@ -8466,36 +8466,26 @@ static void nvme_pci_reset(DeviceState *qdev)
> > nvme_ctrl_reset(n, NVME_RESET_FUNCTION);
> > }
> >
> > -static void nvme_sriov_pre_write_ctrl(PCIDevice *dev, uint32_t address,
> > - uint32_t val, int len)
> > +static void nvme_sriov_post_write_config(PCIDevice *dev, uint16_t
> > old_num_vfs)
> > {
> > NvmeCtrl *n = NVME(dev);
> > NvmeSecCtrlEntry *sctrl;
> > - uint16_t sriov_cap = dev->exp.sriov_cap;
> > - uint32_t off = address - sriov_cap;
> > - int i, num_vfs;
> > + int i;
> >
> > - if (!sriov_cap) {
> > - return;
> > - }
> > -
> > - if (range_covers_byte(off, len, PCI_SRIOV_CTRL)) {
> > - if (!(val & PCI_SRIOV_CTRL_VFE)) {
> > - num_vfs = pci_get_word(dev->config + sriov_cap +
> > PCI_SRIOV_NUM_VF);
> > - for (i = 0; i < num_vfs; i++) {
> > - sctrl = &n->sec_ctrl_list.sec[i];
> > - nvme_virt_set_state(n, le16_to_cpu(sctrl->scid), false);
> > - }
> > - }
> > + for (i = pcie_sriov_num_vfs(dev); i < old_num_vfs; i++) {
> > + sctrl = &n->sec_ctrl_list.sec[i];
> > + nvme_virt_set_state(n, le16_to_cpu(sctrl->scid), false);
> > }
> > }
>
> Maybe I'm missing something, but if the concern is that 'i' could run
> beyond the end of the array, I don't see anything that limits
> pcie_sriov_num_vfs() to the static size of 127 that n->sec_ctrl_list.sec
> has. register_vfs() seems to just take whatever 16 bit value the guest
> wrote without imposing additional restrictions.
>
Hi Kevin,
Thanks for reviewing, I believe patch 2 in this series fixes that
missing validation of NumVFs.
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[PATCH v6 02/15] pcie_sriov: Validate NumVFs, Akihiko Odaki, 2024/02/20