From 2d18434c1ca66d68f80954be6828a3770176dab4 Mon Sep 17 00:00:00 2001 From: Mauro Matteo Cascella Date: Fri, 10 Jul 2020 11:19:41 +0200 Subject: [PATCH] hw/net/xgmac: Fix buffer overflow in xgmac_enet_send() 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 Signed-off-by: Mauro Matteo Cascella Reviewed-by: Peter Maydell Signed-off-by: Jason Wang --- 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 f49df95b07..f496f7ed4c 100644 --- a/hw/net/xgmac.c +++ b/hw/net/xgmac.c @@ -217,21 +217,31 @@ 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); -- 2.23.0