[Spice-devel] [spice-gtk v1 1/2] channel-webdav: implement channel-reset

[Victor Toso]

From: Victor Toso <me at victortoso.com>

The channel can be reset after disabling the shared-folder. If we had
pending read, we should cancel it using the GCancellable for the
demuxing code on vmcstream.c (c->cancellable) and per client operation
(client->cancellable) which is done on client_remove_unref() called by
g_hash_table_unref() in this patch.

This bug resolves rhbz#1474074 for Linux guests, tested on Fedora 25.

Reproducer:
 1. With remote-viewer, connect to a Fedora 25 (GNOME) with
    spice-webavd running;
 2. In remote-viewer, enable shared-folder (File > Preferences);
 3. In the guest, open Nautilus, go to "Other Locations" and double
    click at "Spice client folder" to mount that webdav folder;
 4. Wait for the folder to be mounted in the guest;
 5. In remote-viewer, disabled shared-folder;
 6. In the guest, try to access the mounted folder. It should fail and
    the mount point will be removed;
 7. Repeat steps 2->3 and see the client crash.

> Thread 1 "remote-viewer" received signal SIGSEGV, Segmentation fault.
> (gdb) bt full
> #0  in __memmove_avx_unaligned_erms () from /lib64/libc.so.6
> #1  in spice_channel_read_sasl (channel=0xca8130, data=0xfc2050, len=6) at spice-channel.c:1122
> #2  in spice_channel_read (channel=0xca8130, data=0xfc2050, length=6) at spice-channel.c:1149
> #3  in spice_channel_recv_msg (channel=0xca8130,
      msg_handler=0x7ffff4e52e3c <spice_webdav_handle_msg>, data=0x0) at spice-channel.c:2031
> #4  in spice_channel_iterate_read (channel=0xca8130) at spice-channel.c:2338
> #5  in spice_channel_iterate (channel=0xca8130) at spice-channel.c:2376
> #6  in spice_channel_coroutine (data=0xca8130) at spice-channel.c:2664
> #7  0x00007ffff4e92d49 in coroutine_trampoline (cc=0xca77e0) at coroutine_ucontext.c:63
> #8  0x00007ffff4e92a01 in continuation_trampoline (i0=13268960, i1=0) at continuation.c:55
> #9  0x00007fffefce7600 in ?? () from /lib64/libc.so.6

Related: https://bugzilla.redhat.com/show_bug.cgi?id=1474074

Signed-off-by: Victor Toso <victortoso at redhat.com>
---
 src/channel-webdav.c | 23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

diff --git a/src/channel-webdav.c b/src/channel-webdav.c
index 4a246b5..a4e2215 100644
--- a/src/channel-webdav.c
+++ b/src/channel-webdav.c
@@ -563,7 +563,29 @@ static void spice_webdav_channel_dispose(GObject *object)
 
 static void spice_webdav_channel_up(SpiceChannel *channel)
 {
+    SpiceWebdavChannelPrivate *c = SPICE_WEBDAV_CHANNEL(channel)->priv;
+
     CHANNEL_DEBUG(channel, "up");
+
+    if (c->stream == NULL) {
+        /* In case the channel has been reset */
+        spice_webdav_channel_init(SPICE_WEBDAV_CHANNEL(channel));
+    }
+}
+
+static void spice_webdav_channel_reset(SpiceChannel *channel, gboolean migrating)
+{
+    SpiceWebdavChannel *self = SPICE_WEBDAV_CHANNEL(channel);
+    SpiceWebdavChannelPrivate *c = self->priv;
+
+    c->demuxing = FALSE;
+    g_cancellable_cancel(c->cancellable);
+    g_clear_object(&c->cancellable);
+    g_hash_table_unref(c->clients);
+    g_clear_pointer(&c->queue, output_queue_free);
+    g_clear_object(&c->stream);
+
+    SPICE_CHANNEL_CLASS(spice_webdav_channel_parent_class)->channel_reset(channel, migrating);
 }
 
 static void spice_webdav_channel_class_init(SpiceWebdavChannelClass *klass)
@@ -575,6 +597,7 @@ static void spice_webdav_channel_class_init(SpiceWebdavChannelClass *klass)
     gobject_class->finalize     = spice_webdav_channel_finalize;
     channel_class->handle_msg   = spice_webdav_handle_msg;
     channel_class->channel_up   = spice_webdav_channel_up;
+    channel_class->channel_reset = spice_webdav_channel_reset;
 
     g_signal_override_class_handler("port-event",
                                     SPICE_TYPE_WEBDAV_CHANNEL,
-- 
2.13.0