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Re: [PATCH] pci: assert configuration access is within bounds
From: |
Michael S. Tsirkin |
Subject: |
Re: [PATCH] pci: assert configuration access is within bounds |
Date: |
Thu, 4 Jun 2020 07:41:22 -0400 |
On Thu, Jun 04, 2020 at 05:05:25PM +0530, P J P wrote:
> From: Prasad J Pandit <pjp@fedoraproject.org>
>
> While accessing PCI configuration bytes, assert that
> 'address + len' is within PCI configuration space.
>
> Generally it is within bounds. This is more of a defensive
> assert, in case a buggy device was to send 'address' which
> may go out of bounds.
>
> Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
> Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
> ---
> hw/pci/pci.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> Update v1: defensive assert as separate patch
> -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00957.html
> -> https://lists.gnu.org/archive/html/qemu-devel/2020-06/msg00960.html
>
> diff --git a/hw/pci/pci.c b/hw/pci/pci.c
> index 70c66965f5..7bf2ae6d92 100644
> --- a/hw/pci/pci.c
> +++ b/hw/pci/pci.c
> @@ -1381,6 +1381,8 @@ uint32_t pci_default_read_config(PCIDevice *d,
> {
> uint32_t val = 0;
>
> + assert(address + len <= pci_config_size(d));
> +
> if (pci_is_express_downstream_port(d) &&
> ranges_overlap(address, len, d->exp.exp_cap + PCI_EXP_LNKSTA, 2)) {
> pcie_sync_bridge_lnk(d);
> @@ -1394,6 +1396,8 @@ void pci_default_write_config(PCIDevice *d, uint32_t
> addr, uint32_t val_in, int
> int i, was_irq_disabled = pci_irq_disabled(d);
> uint32_t val = val_in;
>
> + assert(addr + l <= pci_config_size(d));
> +
> for (i = 0; i < l; val >>= 8, ++i) {
> uint8_t wmask = d->wmask[addr + i];
> uint8_t w1cmask = d->w1cmask[addr + i];
> --
> 2.26.2