xcb_query_pointer_reply() and xcb_get_geometry_reply() can return NULL if e.g. the X server closes or the connection is lost. This needs to be checked in order to cleanly exit, because the returned pointers are dereferenced later. Signed-off-by: Moritz Barsnick <barsnick@gmx.net> --- libavdevice/xcbgrab.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/libavdevice/xcbgrab.c b/libavdevice/xcbgrab.c index 6d142abd4f..ccab777c6e 100644 --- a/libavdevice/xcbgrab.c +++ b/libavdevice/xcbgrab.c @@ -404,7 +404,16 @@ static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt) pc = xcb_query_pointer(c->conn, c->screen->root); gc = xcb_get_geometry(c->conn, c->screen->root); p = xcb_query_pointer_reply(c->conn, pc, NULL); + if (!p) { + av_log(c, AV_LOG_ERROR, "Cannot get xcb pointer\n"); + return AVERROR(EIO); + } geo = xcb_get_geometry_reply(c->conn, gc, NULL); + if (!geo) { + av_log(c, AV_LOG_ERROR, "Cannot get xcb geometry\n"); + free(p); + return AVERROR(EIO); + } } if (c->follow_mouse && p->same_screen) @@ -537,6 +546,10 @@ static int create_stream(AVFormatContext *s) gc = xcb_get_geometry(c->conn, c->screen->root); geo = xcb_get_geometry_reply(c->conn, gc, NULL); + if (!geo) { + av_log(c, AV_LOG_ERROR, "Cannot get xcb geometry\n"); + return AVERROR(EIO); + } if (c->x + c->width > geo->width || c->y + c->height > geo->height) { -- 2.14.4