Re: [PATCH for-8.0] ui/vnc: fix bad address parsing

[Vladimir Sementsov-Ogievskiy]

On 12/6/22 23:12, Philippe Mathieu-Daudé wrote:
> On 6/12/22 20:23, Vladimir Sementsov-Ogievskiy wrote:
> > IF addrstr == "[" and websocket is true, hostlen becomes 0 and we try
> > to access addrstr[hostlen-1] which is bad idea.
> >
> > Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
> > ---
> >   ui/vnc.c | 2 +-
> >   1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/ui/vnc.c b/ui/vnc.c
> > index 88f55cbf3c..8830bfe382 100644
> > --- a/ui/vnc.c
> > +++ b/ui/vnc.c
> > @@ -3765,7 +3765,7 @@ static int vnc_display_get_address(const char *addrstr,
> >           addr->type = SOCKET_ADDRESS_TYPE_INET;
> >           inet = &addr->u.inet;
> > -        if (addrstr[0] == '[' && addrstr[hostlen - 1] == ']') {
> > +        if (hostlen >= 2 && addrstr[0] == '[' && addrstr[hostlen - 1] == ']') {
> >               inet->host = g_strndup(addrstr + 1, hostlen - 2);
> >           } else {
> >               inet->host = g_strndup(addrstr, hostlen);
>
> If addrstr is "[" then inet->host ends up being "[" too now, right?
>
> I was pretty sure we had a helper for that, but can't find any.

that's all a bit strange, let's add a bit of debugging:
diff --git a/ui/vnc.c b/ui/vnc.c
index 88f55cbf3c..b1d463e67a 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -3770,6 +3770,7 @@ static int vnc_display_get_address(const char *addrstr,
         } else {
             inet->host = g_strndup(addrstr, hostlen);
         }
+        printf("%s: websocket: %d, host: %s, port: %s\n", __func__, websocket, 
inet->host, port);
         /* plain VNC port is just an offset, for websocket
          * port is absolute */
         if (websocket) {


then:



./build/qemu-system-x86_64 -vnc [
qemu-system-x86_64: -vnc [: no vnc port specified


./build/qemu-system-x86_64 -vnc [,websocket
qemu-system-x86_64: -vnc [,websocket: warning: short-form boolean option 
'websocket' deprecated
Please use websocket=on instead
qemu-system-x86_64: -vnc [,websocket: no vnc port specified



./build/qemu-system-x86_64 -vnc [:0,websocket
qemu-system-x86_64: -vnc [:0,websocket: warning: short-form boolean option 
'websocket' deprecated
Please use websocket=on instead
vnc_display_get_address: websocket: 0, host: [, port: 0
vnc_display_get_address: websocket: 1, host: , port: on
qemu-system-x86_64: -vnc [:0,websocket: address resolution failed for [:5900: 
Name or service not known

./build/qemu-system-x86_64 -vnc [:0,websocket=on
vnc_display_get_address: websocket: 0, host: [, port: 0
vnc_display_get_address: websocket: 1, host: , port: on
qemu-system-x86_64: -vnc [:0,websocket=on: address resolution failed for 
[:5900: Name or service not known


so, "on" is treated as address string? (aha, that's OK, and it's parsed later 
in the code)

./build/qemu-system-x86_64 -vnc :0,websocket=[
vnc_display_get_address: websocket: 0, host: , port: 0
we are going to do bad thing!
vnc_display_get_address: websocket: 1, host: , port: [
qemu-system-x86_64: -vnc :0,websocket=[: address resolution failed for :[: 
Servname not supported for ai_socktype


--
Best regards,
Vladimir