On Tue, 2015-09-29 at 12:23 +0200, Victor Toso wrote: > Hey, > > On Tue, Sep 29, 2015 at 11:53:40AM +0200, Christophe Fergeau wrote: > > When redirecting a USB webcam over a slow link, it's currently possible > > to hit an assertion in spice-server by running cheese (application using > > the webcam), killing the client with ctrl+c and then restarting the > > client: > > qemu-kvm: spicevmc.c:324: spicevmc_red_channel_alloc_msg_rcv_buf: > > Assertion `!state->recv_from_client_buf' failed. > > > > This happens when red_peer_handle_incoming tries to allocate memory for > > a message using spicevmc: > > handler->msg = handler->cb->alloc_msg_buf(handler->opaque, msg_type, > > msg_size); > > > > red_peer_handle_incoming() is called when there is client data to be > > read, and does > > - call alloc_msg_buf() to allocate memory for the message > > - read the message > > - if the read was partial, return early, the main loop will call again > > red_peer_handle_incoming() when there is more data available for that > > channel > > - parse the message > > - call release_msg_buf() to free the message > > > > For channels based on spicevmc (usbredir and port), alloc_msg_buf() > > stores message data in SpiceVmcState::recv_from_client_buf and before > > allocating new memory, it asserts that it's NULL. > > This is a great description of message/memory handling in this channels. > > > > > This is what causes this crash in the following scenario: > > - SpiceVmc::alloc_msg_buf() is called and allocates memory for a new > > message in SpiceVmcState::recv_from_client_buf > > - red_peer_handle_incoming() returns early as all the spicevmc message > > data hasn't been received yet > > - the client gets killed > > - the main channel notices the disconnect and calls > > main_dispatcher_client_disconnect() which will disconnect all the > > channels > > - SpiceVmc::on_disconnect is called > > - after the new client connects, SpiceVmc::alloc_msg_buf() is called, > > notices that SpiceVmcState::recv_from_client_buf is already set, and > > asserts() > > > > This commit makes sure the partial SpiceVmcState::recv_from_client_buf > > data is cleared on disconnect so that the assert does not trigger. > > > > This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1264113 > > --- > > server/spicevmc.c | 5 +++++ > > 1 file changed, 5 insertions(+) > > > > diff --git a/server/spicevmc.c b/server/spicevmc.c > > index e10f183..80f3aeb 100644 > > --- a/server/spicevmc.c > > +++ b/server/spicevmc.c > > @@ -223,6 +223,11 @@ static void > > spicevmc_red_channel_client_on_disconnect(RedChannelClient *rcc) > > sin = state->chardev_sin; > > sif = SPICE_CONTAINEROF(sin->base.sif, SpiceCharDeviceInterface, base); > > > > + if (state->recv_from_client_buf) { /* partial message which wasn't > > pushed to device */ > > + spice_char_device_write_buffer_release(state->chardev_st, state > > ->recv_from_client_buf); > > + state->recv_from_client_buf = NULL; > > + } > > + > > if (state->chardev_st) { > > if (spice_char_device_client_exists(state->chardev_st, rcc > > ->client)) { > > spice_char_device_client_remove(state->chardev_st, rcc > > ->client); > > -- > > 2.5.0 > > That's make sense. Have you tested this on migration as well? > IIRC channel is disconnected during migration. > > cheers, > toso > _______________________________________________ > Spice-devel mailing list > Spice-devel@xxxxxxxxxxxxxxxxxxxxx > http://lists.freedesktop.org/mailman/listinfo/spice-devel Hi Christophe, I just ran across this patch while looking through some bugs and noticed that it doesn't seem to ever have gone upstream. Is it still necessary? Jonathon _______________________________________________ Spice-devel mailing list Spice-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/spice-devel