Re: [Qemu-devel] [PATCH] net: mcf: check buffer descriptor length

[P J P <ppandit@redhat.com>]

+-- On Wed, 21 Sep 2016, Paolo Bonzini wrote --+
| On 21/09/2016 15:45, P J P wrote:
| >          DPRINTF("tx_bd %x flags %04x len %d data %08x\n",
| >                  addr, bd.flags, bd.length, bd.data);
| > -        if ((bd.flags & FEC_BD_R) == 0) {
| > +        if (!bd.length || (bd.flags & FEC_BD_R) == 0) {
| >              /* Run out of descriptors to transmit.  */
| >              break;
| >          }
| 
| Is this a bug?

  Yes, a guest user can control the contents of buffer descriptor 'bd' and 
could set its length to zero and bd.flags to FEC_BD_R; Thus making the loop 
run infinite iterations.

Thank you.
--
Prasad J Pandit / Red Hat Product Security Team
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