[libvirt] [PATCH v3 4/5] tools: console: check if console was shutdown in callbacks

[Cole Robinson]

On 3/18/19 5:08 AM, Nikolay Shirokovskiy wrote:
> On error in main thread virConsoleShutdown is called which
> deletes fd watches/stream callback and yet callbacks can
> be called after. Thus we can incorrectly allocate
> terminalToStream.data memory and get memory leak for example.
> Let's check if console was shutdown in the very beginning of
> callbacks.
> 
> Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy at virtuozzo.com>
> ---
>  tools/virsh-console.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/tools/virsh-console.c b/tools/virsh-console.c
> index 3dae707..d109734 100644
> --- a/tools/virsh-console.c
> +++ b/tools/virsh-console.c
> @@ -139,6 +139,10 @@ virConsoleEventOnStream(virStreamPtr st,
>  
>      virObjectLock(con);
>  
> +    /* we got late event after console was shutdown */
> +    if (!con->st)
> +        goto cleanup;
> +
>      if (events & VIR_STREAM_EVENT_READABLE) {
>          size_t avail = con->streamToTerminal.length -
>              con->streamToTerminal.offset;
> @@ -219,6 +223,10 @@ virConsoleEventOnStdin(int watch ATTRIBUTE_UNUSED,
>  
>      virObjectLock(con);
>  
> +    /* we got late event after console was shutdown */
> +    if (!con->st)
> +        goto cleanup;
> +
>      if (events & VIR_EVENT_HANDLE_READABLE) {
>          size_t avail = con->terminalToStream.length -
>              con->terminalToStream.offset;
> @@ -279,6 +287,10 @@ virConsoleEventOnStdout(int watch ATTRIBUTE_UNUSED,
>  
>      virObjectLock(con);
>  
> +    /* we got late event after console was shutdown */
> +    if (!con->st)
> +        goto cleanup;
> +
>      if (events & VIR_EVENT_HANDLE_WRITABLE &&
>          con->streamToTerminal.offset) {
>          ssize_t done;
> 

I didn't verify exactly how this case can happen but it seems sane, so:

Reviewed-by: Cole Robinson <crobinso at redhat.com>

- Cole