[Spice-devel] [spice-gtk v2] file-xfer: fix segfault on agent disconnection

[Fabiano Fidêncio]

On May 14, 2016 17:29, "Victor Toso" <victortoso at redhat.com> wrote:
>
> We are checking self->priv->error but accessing the argument GError *
> which is NULL and leads to a segfault.
>
> Program received signal SIGSEGV, Segmentation fault.
> spice_file_transfer_task_completed (self=self at entry=0x7fffd0006f00,
error=0x0) at channel-main.c:2963
> 2963            VDAgentFileXferStatusMessage msg = {
> (gdb) bt
>  #0  spice_file_transfer_task_completed (self=self at entry=0x7fffd0006f00,
error=0x0) at channel-main.c:2963
>  #1  in file_xfer_data_flushed_cb (source_object=0x7cc1d0, res=0x953390,
user_data=user_data at entry=0x7fffd0006f00) at channel-main.c:1857
>  #2  in g_task_return_now (task=0x953390) at gtask.c:1108
>  #3  in g_task_return (task=0x953390, type=<optimized out>) at
gtask.c:1166
>  #4  in flush_foreach_remove (key=<optimized out>, value=<optimized out>,
user_data=<optimized out>) at channel-main.c:928
>  #5  in g_hash_table_foreach_remove_or_steal (hash_table=0x70cea0,
func=func at entry=0x7ffff5616f10 <flush_foreach_remove>,
user_data=user_data at entry=0x0, notify=notify at entry=1) at ghash.c:1492
>  #6  in g_hash_table_foreach_remove (hash_table=<optimized out>,
func=func at entry=0x7ffff5616f10 <flush_foreach_remove>,
user_data=user_data at entry=0x0) at ghash.c:1538
>  #7  in file_xfer_flushed (success=0, channel=0x7cc1d0) at
channel-main.c:936
>  #8  spice_main_channel_reset_agent (channel=0x7cc1d0) at
channel-main.c:466
>  #9  set_agent_connected (channel=0x7cc1d0, connected=connected at entry=0)
at channel-main.c:1572
>  #10 in spice_main_channel_reset (channel=0x7cc1d0, migrating=0) at
channel-main.c:485
>  #11 in spice_channel_coroutine (data=0x7cc1d0) at spice-channel.c:2564
>  #12 in coroutine_trampoline (cc=0x7cb860) at coroutine_ucontext.c:63
>  #13 in continuation_trampoline (i0=<optimized out>, i1=<optimized out>)
at continuation.c:55
>  #14 in ?? () from /lib64/libc.so.6
>  #15 in ?? ()
>  #16 in ?? ()
> Backtrace stopped: Cannot access memory at address
> ---
>  src/channel-main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/src/channel-main.c b/src/channel-main.c
> index 2905d7b..692cfe7 100644
> --- a/src/channel-main.c
> +++ b/src/channel-main.c
> @@ -2964,7 +2964,7 @@ static void
spice_file_transfer_task_completed(SpiceFileTransferTask *self,
>      if (self->priv->error) {
>          VDAgentFileXferStatusMessage msg = {
>              .id = self->priv->id,
> -            .result = error->code == G_IO_ERROR_CANCELLED ?
> +            .result = self->priv->error->code == G_IO_ERROR_CANCELLED ?
>                      VD_AGENT_FILE_XFER_STATUS_CANCELLED :
VD_AGENT_FILE_XFER_STATUS_ERROR,
>          };
>          agent_msg_queue_many(self->priv->channel,
VD_AGENT_FILE_XFER_STATUS,
> --
> 2.5.5
>

Victor, as we talked on IRC your patch solves the problem, fust to comments:

First one, shouldn't we emmit self->priv->error instead of error in the end
of this function?

Second one, from a quick look in the code, I have the impression that we
can get rid of the private Error variable and just use the error that we
are propagating between the callbacks. A deeper read in the code would be
needed though in order to affirm that.

Best Regards,
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