Overview
About vulnerability
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.
Details
- Affected product:
- Ubuntu 20.04 ELS
- Affected packages:
- linux-meta @ 5.4.0 (+1 more)
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.