diff mbox series

[PULL,2/2] hw/net/xgmac: Fix buffer overflow in xgmac_enet_send()

Message ID 1595338467-19556-3-git-send-email-jasowang@redhat.com
State New
Headers show
Series [PULL,1/2] hw/net: Added plen fix for IPv6 | expand

Commit Message

Jason Wang July 21, 2020, 1:34 p.m. UTC
From: Mauro Matteo Cascella <mcascell@redhat.com>

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 mbox series

Patch

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);