Commit cde31a0e authored by Jason Wang's avatar Jason Wang Committed by Michael S. Tsirkin
Browse files

rtl8139: limit transmission buffer size in c+ mode 



The tx buffer would be re-allocated for tx descriptor with big size
and without LS bit set, this would make guest driver could easily let
qemu to allocate unlimited.

In linux host, a glib failure were easy to be triggered:

GLib-ERROR **: gmem.c:176: failed to allocate 18446744071562067968 bytes

This patch fix this by adding a limit. As the spec didn't tell the maximum size
of buffer allowed, stick it to current CP_TX_BUFFER_SIZE (65536).

Changes from V1:

Drop the while statement and s->cplus_txbuffer check.

Signed-off-by: default avatarJason Wang <jasowang@redhat.com>
Reviewed-by: default avatarStefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
parent 453058d3

hw/rtl8139.c

+5 −6
Original line number Diff line number Diff line
@@ -2061,13 +2061,12 @@ static int rtl8139_cplus_transmit_one(RTL8139State *s) 
            s->cplus_txbuffer_len);

    }



    while (s->cplus_txbuffer && s->cplus_txbuffer_offset + txsize >= s->cplus_txbuffer_len)

    if (s->cplus_txbuffer_offset + txsize >= s->cplus_txbuffer_len)

    {

        s->cplus_txbuffer_len += CP_TX_BUFFER_SIZE;

        s->cplus_txbuffer = g_realloc(s->cplus_txbuffer, s->cplus_txbuffer_len);



        DPRINTF("+++ C+ mode transmission buffer space changed to %d\n",

            s->cplus_txbuffer_len);

        /* The spec didn't tell the maximum size, stick to CP_TX_BUFFER_SIZE */

        txsize = s->cplus_txbuffer_len - s->cplus_txbuffer_offset;

        DPRINTF("+++ C+ mode transmission buffer overrun, truncated descriptor"

                "length to %d\n", txsize);

    }



    if (!s->cplus_txbuffer)