On 09/25/2018 01:27 PM, Tong Zhang wrote:
Kernel Version: 4.18.5 Problem Description: When setting nice value, it is checked by LSM function security_task_setnice(). see kernel/sched/core.c:3972 SYSCALL_DEFINE1(nice, int, increment) We discovered a leaking path in android binder which allows using binder’s interface to change a process’s nice value. This path is leaked from being monitored by LSM. see drivers/android/binder.c:1107 binder_set_nice.
Not sure you want to invoke the LSM hook (or at least the same hook) when binder is performing priority inheritance. There is a difference between a userspace process switching its own priority and the kernel binder driver performing it. IIUC, the can_nice() check is more about honoring RLIMIT_NICE than anything else.
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