[Spice-devel] [spice-server PATCH v2 3/3] dcc-send: fix use-after-free

Uri Lublin uril at redhat.com
Wed Jul 10 17:44:35 UTC 2019


'l' is being freed within the loop

Found-by: Frediano Ziglio <fziglio at redhat.com>
Signed-off-by: Uri Lublin <uril at redhat.com>
---
 server/dcc-send.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/server/dcc-send.c b/server/dcc-send.c
index e0f3b8183..4a92ce8cd 100644
--- a/server/dcc-send.c
+++ b/server/dcc-send.c
@@ -711,7 +711,7 @@ static void red_pipe_replace_rendered_drawables_with_images(DisplayChannelClient
     int resent_surface_ids[MAX_PIPE_SIZE];
     SpiceRect resent_areas[MAX_PIPE_SIZE]; // not pointers since drawables may be released
     int num_resent;
-    GList *l;
+    GList *l, *prev;
     GQueue *pipe;
 
     resent_surface_ids[0] = first_surface_id;
@@ -721,11 +721,12 @@ static void red_pipe_replace_rendered_drawables_with_images(DisplayChannelClient
     pipe = red_channel_client_get_pipe(RED_CHANNEL_CLIENT(dcc));
 
     // going from the oldest to the newest
-    for (l = pipe->tail; l != NULL; l = l->prev) {
+    for (l = pipe->tail; l != NULL; l = prev) {
         RedPipeItem *pipe_item = l->data;
         Drawable *drawable;
         RedDrawablePipeItem *dpi;
 
+        prev = l->prev;
         if (pipe_item->type != RED_PIPE_ITEM_TYPE_DRAW)
             continue;
         dpi = SPICE_UPCAST(RedDrawablePipeItem, pipe_item);
-- 
2.21.0



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