From: Mauro Matteo Cascella <[email protected]> A buffer overflow issue was reported by Mr. Ziming Zhang, CC'd here. It occurs while sending an Ethernet frame due to missing break statements and improper checking of the buffer size.
Reported-by: Ziming Zhang <[email protected]> Signed-off-by: Mauro Matteo Cascella <[email protected]> Reviewed-by: Peter Maydell <[email protected]> Signed-off-by: Jason Wang <[email protected]> --- hw/net/xgmac.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/hw/net/xgmac.c b/hw/net/xgmac.c index 574dd47..5bf1b61 100644 --- a/hw/net/xgmac.c +++ b/hw/net/xgmac.c @@ -220,21 +220,31 @@ static void xgmac_enet_send(XgmacState *s) } len = (bd.buffer1_size & 0xfff) + (bd.buffer2_size & 0xfff); + /* + * FIXME: these cases of malformed tx descriptors (bad sizes) + * should probably be reported back to the guest somehow + * rather than simply silently stopping processing, but we + * don't know what the hardware does in this situation. + * This will only happen for buggy guests anyway. + */ if ((bd.buffer1_size & 0xfff) > 2048) { DEBUGF_BRK("qemu:%s:ERROR...ERROR...ERROR... -- " "xgmac buffer 1 len on send > 2048 (0x%x)\n", __func__, bd.buffer1_size & 0xfff); + break; } if ((bd.buffer2_size & 0xfff) != 0) { DEBUGF_BRK("qemu:%s:ERROR...ERROR...ERROR... -- " "xgmac buffer 2 len on send != 0 (0x%x)\n", __func__, bd.buffer2_size & 0xfff); + break; } - if (len >= sizeof(frame)) { + if (frame_size + len >= sizeof(frame)) { DEBUGF_BRK("qemu:%s: buffer overflow %d read into %zu " - "buffer\n" , __func__, len, sizeof(frame)); + "buffer\n" , __func__, frame_size + len, sizeof(frame)); DEBUGF_BRK("qemu:%s: buffer1.size=%d; buffer2.size=%d\n", __func__, bd.buffer1_size, bd.buffer2_size); + break; } cpu_physical_memory_read(bd.buffer1_addr, ptr, len); -- 2.5.0
