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Re: [Qemu-devel] [RFC PATCH]pci-assign: Fix memory out of bound when MSI
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC PATCH]pci-assign: Fix memory out of bound when MSI-X table not fit in a single page |
Date: |
Tue, 1 Apr 2014 18:45:28 +0300 |
On Tue, Apr 01, 2014 at 03:23:36PM +0000, Gonglei (Arei) wrote:
> Hi,
>
> I have a problem about SR-IOV pass-through.
>
> The PF is Emulex Corporation OneConnect NIC (Lancer)(rev 10),
> and the VF pci config is as follow:
>
> LINUX:/sys/bus/pci/devices/0000:04:00.6 # hexdump config
> 0000000 ffff ffff 0000 0010 0010 0200 0000 0080
> 0000010 0000 0000 0000 0000 0000 0000 0000 0000
> 0000020 0000 0000 0000 0000 0000 0000 10df e264
> 0000030 0000 0000 0054 0000 0000 0000 0000 0000
> 0000040 0000 0000 0008 0000 0000 0000 0000 0000
> 0000050 0000 0000 6009 0008 2b41 c002 0000 0000
> 0000060 7805 018a 0000 0000 0000 0000 0000 0000
> 0000070 0000 0000 0000 0000 8411 03ff 4000 0000
> 0000080 3400 0000 9403 0000 0000 0000 0000 0000
> 0000090 0000 0000 0010 0002 8724 1000 0000 0000
> 00000a0 dc83 0041 0000 0000 0000 0000 0000 0000
> 00000b0 0000 0000 0000 0000 001f 0010 0000 0000
> 00000c0 000e 0000 0000 0000 0000 0000 0000 0000
> 00000d0 0000 0000 0000 0000 0000 0000 0000 0000
>
> We can see the msix_max is 0x3ff and msix_table_entry is 0x4000 (4 pages).
> But QEMU
> only mmap MSIX_PAGE_SIZE memory for all pci devices in funciton
> assigned_dev_register_msix_mmio,
> meanwhile the set the one page memmory to zero, so the rest memory will be
> random value
> (maybe etnry.data is not 0).
>
> In function assigned_dev_update_msix_mmio maybe occur the issue of entry_nr >
> 256,
> and the kmod reports the EINVAL error.
>
> My patch fix this issue which alloc memory according to the real size of pci
> device config.
>
> Any ideas? Thnaks.
>
> Signed-off-by: Gonglei <address@hidden>
> ---
> hw/i386/kvm/pci-assign.c | 24 +++++++++++++++++++-----
> 1 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/hw/i386/kvm/pci-assign.c b/hw/i386/kvm/pci-assign.c
> index a825871..daa191c 100644
> --- a/hw/i386/kvm/pci-assign.c
> +++ b/hw/i386/kvm/pci-assign.c
> @@ -1591,10 +1591,6 @@ static void assigned_dev_msix_reset(AssignedDevice
> *dev)
> MSIXTableEntry *entry;
> int i;
>
> - if (!dev->msix_table) {
> - return;
> - }
> -
> memset(dev->msix_table, 0, MSIX_PAGE_SIZE);
>
> for (i = 0, entry = dev->msix_table; i < dev->msix_max; i++, entry++) {
> @@ -1604,13 +1600,31 @@ static void assigned_dev_msix_reset(AssignedDevice
> *dev)
>
> static int assigned_dev_register_msix_mmio(AssignedDevice *dev)
> {
> - dev->msix_table = mmap(NULL, MSIX_PAGE_SIZE, PROT_READ|PROT_WRITE,
> + int nr_pages;
> + int size;
> + int entry_per_page = MSIX_PAGE_SIZE / sizeof(struct MSIXTableEntry);
> +
> + if (dev->msix_max > entry_per_page) {
> + nr_pages = dev->msix_max / entry_per_page;
> + if (dev->msix_max % entry_per_page) {
> + nr_pages += 1;
> + }
> + } else {
> + nr_pages = 1;
> + }
It's usually not a good idea to special-case corner-cases like this.
> +
> + size = MSIX_PAGE_SIZE * nr_pages;
Just use ROUND_UP?
> + dev->msix_table = mmap(NULL, size, PROT_READ|PROT_WRITE,
> MAP_ANONYMOUS|MAP_PRIVATE, 0, 0);
Need to fix unmap as well?
> if (dev->msix_table == MAP_FAILED) {
> error_report("fail allocate msix_table! %s", strerror(errno));
> return -EFAULT;
> }
> + if (!dev->msix_table) {
> + return -EFAULT;
> + }
>
> + memset(dev->msix_table, 0, size);
> assigned_dev_msix_reset(dev);
>
> memory_region_init_io(&dev->mmio, OBJECT(dev),
> &assigned_dev_msix_mmio_ops,
> --
> 1.6.0.2
>
> Best regards,
> -Gonglei
>