Re: [Qemu-devel] [PATCH] usbredir: fix buffer-overflow on migration load

[Marc-André Lureau]

Hi

On Fri, Jul 5, 2019 at 11:40 AM Marc-André Lureau
<address@hidden> wrote:
>
> NO_INTERFACE_INFO (255) is used to indicate no info.
>
> /home/elmarco/src/qemu/hw/usb/redirect.c:1504:71: runtime error: index 32 out 
> of bounds for type 'uint8_t [32]'
> /home/elmarco/src/qemu/hw/usb/redirect.c:1503:71: runtime error: index 32 out 
> of bounds for type 'uint8_t [32]'
> /home/elmarco/src/qemu/hw/usb/redirect.c:1502:68: runtime error: index 32 out 
> of bounds for type 'uint8_t [32]'
> =================================================================
> ==32073==ERROR: AddressSanitizer: heap-buffer-overflow on address 
> 0x625000252930 at pc 0x556c5126b0b6 bp 0x7fc7793ffa50 sp 0x7fc7793ffa40
> READ of size 1 at 0x625000252930 thread T0
>     #0 0x556c5126b0b5 in usbredir_check_bulk_receiving 
> /home/elmarco/src/qemu/hw/usb/redirect.c:1504
>     #1 0x556c51275a2a in usbredir_post_load 
> /home/elmarco/src/qemu/hw/usb/redirect.c:2154
>     #2 0x556c51306f5e in vmstate_load_state 
> /home/elmarco/src/qemu/migration/vmstate.c:168
>     #3 0x556c512efb43 in vmstate_load 
> /home/elmarco/src/qemu/migration/savevm.c:829
>     #4 0x556c512f9967 in qemu_loadvm_section_start_full 
> /home/elmarco/src/qemu/migration/savevm.c:2212
>     #5 0x556c512faee1 in qemu_loadvm_state_main 
> /home/elmarco/src/qemu/migration/savevm.c:2396
>     #6 0x556c512fb16b in qemu_loadvm_state 
> /home/elmarco/src/qemu/migration/savevm.c:2468
>     #7 0x556c512c0d2b in process_incoming_migration_co 
> /home/elmarco/src/qemu/migration/migration.c:449
>     #8 0x556c51b62bcc in coroutine_trampoline 
> /home/elmarco/src/qemu/util/coroutine-ucontext.c:115
>     #9 0x7fc80fba637f  (/lib64/libc.so.6+0x4d37f)
>
> Cc: address@hidden
> Signed-off-by: Marc-André Lureau <address@hidden>

To be even safer, we should check interface_count has a value <= 32 on load.

> ---
>  hw/usb/redirect.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/hw/usb/redirect.c b/hw/usb/redirect.c
> index 998fc6e4b0..3bda19bd64 100644
> --- a/hw/usb/redirect.c
> +++ b/hw/usb/redirect.c
> @@ -1495,6 +1495,9 @@ static void 
> usbredir_check_bulk_receiving(USBRedirDevice *dev)
>      for (i = EP2I(USB_DIR_IN); i < MAX_ENDPOINTS; i++) {
>          dev->endpoint[i].bulk_receiving_enabled = 0;
>      }
> +    if (dev->interface_info.interface_count == NO_INTERFACE_INFO) {
> +        return;
> +    }
>      for (i = 0; i < dev->interface_info.interface_count; i++) {
>          quirks = usb_get_quirks(dev->device_info.vendor_id,
>                                  dev->device_info.product_id,
> --
> 2.22.0.214.g8dca754b1e
>