[Qemu-devel] [PATCH] char: fix missing return in error path for chardev TLS init

[Qemu-devel] [PATCH] char: fix missing return in error path for chardev TLS init

[Daniel P. Berrange]

If the qio_channel_tls_new_(server|client) methods fail,
we disconnect the client. Unfortunately a missing return
means we then go on to try and run the TLS handshake on
a NULL I/O channel. This gives predictably segfaulty
results.

The main way to trigger this is to request a bogus TLS
priority string for the TLS credentials. e.g.

  -object tls-creds-x509,id=tls0,priority=wibble,...

Most other ways appear impossible to trigger except
perhaps if OOM conditions cause gnutls initialization
to fail.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
---
 qemu-char.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/qemu-char.c b/qemu-char.c
index fb456ce..48a45ef 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -3132,6 +3132,7 @@ static void tcp_chr_tls_init(CharDriverState *chr)
     if (tioc == NULL) {
         error_free(err);
         tcp_chr_disconnect(chr);
+        return;
     }
     object_unref(OBJECT(s->ioc));
     s->ioc = QIO_CHANNEL(tioc);
-- 
2.7.4

Re: [Qemu-devel] [PATCH] char: fix missing return in error path for chardev TLS init

[Eric Blake]

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On 09/30/2016 10:02 AM, Daniel P. Berrange wrote:
> If the qio_channel_tls_new_(server|client) methods fail,
> we disconnect the client. Unfortunately a missing return
> means we then go on to try and run the TLS handshake on
> a NULL I/O channel. This gives predictably segfaulty
> results.
> 
> The main way to trigger this is to request a bogus TLS
> priority string for the TLS credentials. e.g.
> 
>   -object tls-creds-x509,id=tls0,priority=wibble,...
> 
> Most other ways appear impossible to trigger except
> perhaps if OOM conditions cause gnutls initialization
> to fail.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
> ---
>  qemu-char.c | 1 +
>  1 file changed, 1 insertion(+)

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH] char: fix missing return in error path for chardev TLS init

[Michael Tokarev]

30.09.2016 18:02, Daniel P. Berrange wrote:
> If the qio_channel_tls_new_(server|client) methods fail,
> we disconnect the client. Unfortunately a missing return
> means we then go on to try and run the TLS handshake on
> a NULL I/O channel. This gives predictably segfaulty
> results.

Applied to -trivial, thanks!

/mjt