Gerd Hoffmann <kra...@redhat.com> 于2020年8月25日周二 下午1:37写道：
>
> Store calculated setup_len in a local variable, verify it, and only
> write it to the struct (USBDevice->setup_len) in case it passed the
> sanity checks.
>
> This prevents other code (do_token_{in,out} functions specifically)
> from working with invalid USBDevice->setup_len values and overrunning
> the USBDevice->setup_buf[] buffer.
>
> Fixes: CVE-2020-14364
> Signed-off-by: Gerd Hoffmann <kra...@redhat.com>
> Tested-by: Gonglei <arei.gong...@huawei.com>Reviewed-by: Li Qiang <liq...@gmail.com> Just see the page. -->https://access.redhat.com/security/cve/CVE-2020-14364 The 'Attack Vector' of the CVSS score here is 'local'. Hi Prasad, I think this should be 'network' as the guest user can touch this in cloud environment? What's the consideration here? Thanks, Li Qiang > --- > hw/usb/core.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/hw/usb/core.c b/hw/usb/core.c > index 5abd128b6bc5..5234dcc73fea 100644 > --- a/hw/usb/core.c > +++ b/hw/usb/core.c > @@ -129,6 +129,7 @@ void usb_wakeup(USBEndpoint *ep, unsigned int stream) > static void do_token_setup(USBDevice *s, USBPacket *p) > { > int request, value, index; > + unsigned int setup_len; > > if (p->iov.size != 8) { > p->status = USB_RET_STALL; > @@ -138,14 +139,15 @@ static void do_token_setup(USBDevice *s, USBPacket *p) > usb_packet_copy(p, s->setup_buf, p->iov.size); > s->setup_index = 0; > p->actual_length = 0; > - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; > - if (s->setup_len > sizeof(s->data_buf)) { > + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; > + if (setup_len > sizeof(s->data_buf)) { > fprintf(stderr, > "usb_generic_handle_packet: ctrl buffer too small (%d > > %zu)\n", > - s->setup_len, sizeof(s->data_buf)); > + setup_len, sizeof(s->data_buf)); > p->status = USB_RET_STALL; > return; > } > + s->setup_len = setup_len; > > request = (s->setup_buf[0] << 8) | s->setup_buf[1]; > value = (s->setup_buf[3] << 8) | s->setup_buf[2]; > @@ -259,26 +261,28 @@ static void do_token_out(USBDevice *s, USBPacket *p) > static void do_parameter(USBDevice *s, USBPacket *p) > { > int i, request, value, index; > + unsigned int setup_len; > > for (i = 0; i < 8; i++) { > s->setup_buf[i] = p->parameter >> (i*8); > } > > s->setup_state = SETUP_STATE_PARAM; > - s->setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; > s->setup_index = 0; > > request = (s->setup_buf[0] << 8) | s->setup_buf[1]; > value = (s->setup_buf[3] << 8) | s->setup_buf[2]; > index = (s->setup_buf[5] << 8) | s->setup_buf[4]; > > - if (s->setup_len > sizeof(s->data_buf)) { > + setup_len = (s->setup_buf[7] << 8) | s->setup_buf[6]; > + if (setup_len > sizeof(s->data_buf)) { > fprintf(stderr, > "usb_generic_handle_packet: ctrl buffer too small (%d > > %zu)\n", > - s->setup_len, sizeof(s->data_buf)); > + setup_len, sizeof(s->data_buf)); > p->status = USB_RET_STALL; > return; > } > + s->setup_len = setup_len; > > if (p->pid == USB_TOKEN_OUT) { > usb_packet_copy(p, s->data_buf, s->setup_len); > -- > 2.27.0 > >
