In the Linux kernel, the following vulnerability has been resolved:

fgraph: Do not enable function_graph tracer when setting funcgraph-args

When setting the funcgraph-args option when function graph tracer is net enabled, it incorrectly enables it. Worse, it unregisters itself when it was never registered. Then when it gets enabled again, it will register itself a second time causing a WARNing.

~# echo 1 > /sys/kernel/tracing/options/funcgraph-args ~# head -20 /sys/kernel/tracing/trace

tracer: nop

entries-in-buffer/entries-written: 813/26317372 #P:8

_-----=> irqs-off/BH-disabled

/ _----=> need-resched

| / _---=> hardirq/softirq

|| / _--=> preempt-depth

||| / _-=> migrate-disable

|||| / delay

TASK-PID CPU# ||||| TIMESTAMP FUNCTION

| | | ||||| | |

       <idle>-0       [007] d..4.   358.966010:  7)   1.692 us    |          fetch_next_timer_interrupt(basej=4294981640, basem=357956000000, base_local=0xffff88823c3ae040, base_global=0xffff88823c3af300, tevt=0xffff888100e47cb8);
       <idle>-0       [007] d..4.   358.966012:  7)               |          tmigr_cpu_deactivate(nextexp=357988000000) {
       <idle>-0       [007] d..4.   358.966013:  7)               |            _raw_spin_lock(lock=0xffff88823c3b2320) {
       <idle>-0       [007] d..4.   358.966014:  7)   0.981 us    |              preempt_count_add(val=1);
       <idle>-0       [007] d..5.   358.966017:  7)   1.058 us    |              do_raw_spin_lock(lock=0xffff88823c3b2320);
       <idle>-0       [007] d..4.   358.966019:  7)   5.824 us    |            }
       <idle>-0       [007] d..5.   358.966021:  7)               |            tmigr_inactive_up(group=0xffff888100cb9000, child=0x0,...