From a80a85c7c358febb164ace0dfa75c468f43e0f02 Mon Sep 17 00:00:00 2001
From: Mauro Matteo Cascella <mcascell@redhat.com>
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 <ezrakiez@gmail.com>
Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
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