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vnc: fix use-after-free in vnc_update_client_sync 

Spotted by Coverity:

876     static int vnc_update_client_sync(VncState *vs, int has_dirty)
877     {

(1) Event freed_arg:    "vnc_update_client(VncState *, int)" frees "vs".  [details]
Also see events:        [deref_arg]

878         int ret = vnc_update_client(vs, has_dirty);

(2) Event deref_arg:    Calling "vnc_jobs_join(VncState *)" dereferences freed pointer "vs". [details]
Also see events:        [freed_arg]

879         vnc_jobs_join(vs);
880         return ret;
881     }

Remove vnc_update_client_sync wrapper, replace it with an additional
argument to vnc_update_client, so we can so the sync properly in
vnc_update_client (i.e. skip it in case of a client disconnect).

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
This commit is contained in:
Gerd Hoffmann 2014-03-06 13:54:28 +01:00
parent e3c1adf16e
commit 38ee14f4f3
1 changed files with 8 additions and 13 deletions
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21
ui/vnc.c
View File

@ -417,8 +417,7 @@ out_error:
3) resolutions > 1024
*/
static int vnc_update_client(VncState *vs, int has_dirty);
static int vnc_update_client_sync(VncState *vs, int has_dirty);
static int vnc_update_client(VncState *vs, int has_dirty, bool sync);
static void vnc_disconnect_start(VncState *vs);
static void vnc_colordepth(VncState *vs);
@ -751,7 +750,7 @@ static void vnc_dpy_copy(DisplayChangeListener *dcl,
QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
vs->force_update = 1;
vnc_update_client_sync(vs, 1);
vnc_update_client(vs, 1, true);
/* vs might be free()ed here */
}
}
@ -874,14 +873,7 @@ static int find_and_clear_dirty_height(struct VncState *vs,
return h;
}
static int vnc_update_client_sync(VncState *vs, int has_dirty)
{
int ret = vnc_update_client(vs, has_dirty);
vnc_jobs_join(vs);
return ret;
}
static int vnc_update_client(VncState *vs, int has_dirty)
static int vnc_update_client(VncState *vs, int has_dirty, bool sync)
{
if (vs->need_update && vs->csock != -1) {
VncDisplay *vd = vs->vd;
@ -940,8 +932,11 @@ static int vnc_update_client(VncState *vs, int has_dirty)
return n;
}
if (vs->csock == -1)
if (vs->csock == -1) {
vnc_disconnect_finish(vs);
} else if (sync) {
vnc_jobs_join(vs);
}
return 0;
}
@ -2734,7 +2729,7 @@ static void vnc_refresh(DisplayChangeListener *dcl)
vnc_unlock_display(vd);
QTAILQ_FOREACH_SAFE(vs, &vd->clients, next, vn) {
rects += vnc_update_client(vs, has_dirty);
rects += vnc_update_client(vs, has_dirty, false);
/* vs might be free()ed here */
}