Commit 587d60d2b7 ('Add AP mode support
for HT 20/40 co-ex Action frame') added processing of co-ex report, but
did not include proper bounds checking or IE type checking for the
payload. Furthermore, this was not ready for the possible extensibility
of the 20/40 BSS Coexistence element.
Fix these by checking IE ids for both elements and doing more
apprioriate bounds checking for the element lengths to avoid potentially
reading beyond the frame buffer. Though, the event receive buffer in
both libnl and driver_nl80211_monitor.c is sufficiently large to make it
very unlikely that the maximum read of about 260 bytes beyond the end of
the Action frame would really have any chances of hitting the end of the
memory buffer, so the practical effect of missing bounds checking would
have been possibly accepting an invalid report frame and moving to 20
MHz channel unnecessarily.
Signed-off-by: Jouni Malinen <j@w1.fi>