An upgrade is required to resolve this issue completely. Sourcefire 4.8.0 is the last release that relied on the ips-accel module. Starting from XOS 8.5 and Sourcefire 4.8.2 the architecture changed to use VNIM instead of ips-accel and new versions don't suffer from this issue.
As a workaround and to avoid filling up the hard drive, you can change the syslog configuration on the VAPs running Sourcefire to filter out kernel warning messages. Here are the instructions to disable sending of kernel messages at level "warning" to the CPM:
1) Change to CPM unix prompt:
CBS# unix su
2) Login to the Sourcefire VAP with rsh:
3) Edit the configuration file /etc/syslog.conf. Find the following line within the file:
Change the line so it looks like this:
4) Save the file and restart syslog:
ips_1 (CBS): root$ /etc/init.d/syslog restart
The steps 2-4 need to be repeated for every Sourcefire VAP group member.