In the Linux kernel, the following vulnerability has been resolved:
netfilter: xt_IDLETIMER: reject rev0 reuse of ALARM timer labels
IDLETIMER revision 0 rules reuse existing timers by label and always call mod_timer() on timer->timer.
If the label was created first by revision 1 with XT_IDLETIMER_ALARM, the object uses alarm timer semantics and timer->timer is never initialized. Reusing that object from revision 0 causes mod_timer() on an uninitialized timer_list, triggering debugobjects warnings and possible panic when panic_on_warn=1.
Fix this by rejecting revision 0 rule insertion when an existing timer with the same label is of ALARM type.
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:H7.8/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H