Invalid memory access in xcb_icccm_get_wm_class_from_reply
Submitted by jpi..@..ree.fr
Assigned to xcb mailing list dummy
I fell in a case where in xcb_icccm_get_wm_class_from_reply, the reply was empty, i.e., in following snippet from icccm.c, len was 0, and reply->length was 0 also.
int len = xcb_get_property_value_length(prop->_reply);
< reply->length * 4)
prop->instance_name[len] = 0;
prop->instance_name[len-1] = 0;
in this case, prop->instance_name[-1] is set to 0, and the following strlen(prop->instance_name) may access invalid memory.
This may be reproduced under openbox window manager, under which there is this window triggering the bug :
If xwininfo is compiled without icccm : ./xwininfo -tree -root | grep Openbox 0xe0008b "Openbox": ("" (none)) 1x1+-100+-100 +-100+-100
If xwininfo is compiled with icccm :
./xwininfo -tree -root | grep Openbox
0xe0008b "Openbox": ("" "") 1x1+-100+-100 +-100+-100
The second case triggers the Invalid memory access