tap-win32: correctly recycle buffers

Commit 969e50b61a28 ("net: Pad short frames to minimum size before
sending from SLiRP/TAP") tries to pad frames but try to recyle the
local array that is used for padding to tap thread. This patch fixes
this by recyling the original buffer.

Fixes: 969e50b61a28 ("net: Pad short frames to minimum size before sending from SLiRP/TAP")
Tested-by: Howard Spoelstra <hsp.cat7@gmail.com>
Tested-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/net/tap-win32.c b/net/tap-win32.c
index fb92b55768..897bd18e32 100644
--- a/net/tap-win32.c
+++ b/net/tap-win32.c
@@ -686,7 +686,7 @@ static ssize_t tap_receive(NetClientState *nc, const uint8_t *buf, size_t size)
 static void tap_win32_send(void *opaque)
 {
     TAPState *s = opaque;
-    uint8_t *buf;
+    uint8_t *buf, *orig_buf;
     int max_size = 4096;
     int size;
     uint8_t min_pkt[ETH_ZLEN];
@@ -694,6 +694,8 @@ static void tap_win32_send(void *opaque)
 
     size = tap_win32_read(s->handle, &buf, max_size);
     if (size > 0) {
+        orig_buf = buf;
+
         if (!s->nc.peer->do_not_pad) {
             if (eth_pad_short_frame(min_pkt, &min_pktsz, buf, size)) {
                 buf = min_pkt;
@@ -702,7 +704,7 @@ static void tap_win32_send(void *opaque)
         }
 
         qemu_send_packet(&s->nc, buf, size);
-        tap_win32_free_buffer(s->handle, buf);
+        tap_win32_free_buffer(s->handle, orig_buf);
     }
 }