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![Thomas Gleixner](/assets/img/avatar_default.png)
The posix timer overrun handling is broken because the forwarding functions can return a huge number of overruns which does not fit in an int. As a consequence timer_getoverrun(2) and siginfo::si_overrun can turn into random number generators. The k_clock::timer_forward() callbacks return a 64 bit value now. Make k_itimer::ti_overrun[_last] 64bit as well, so the kernel internal accounting is correct. 3Remove the temporary (int) casts. Add a helper function which clamps the overrun value returned to user space via timer_getoverrun(2) or siginfo::si_overrun limited to a positive value between 0 and INT_MAX. INT_MAX is an indicator for user space that the overrun value has been clamped. Reported-by: Team OWL337 <icytxw@gmail.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Acked-by: John Stultz <john.stultz@linaro.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Michael Kerrisk <mtk.manpages@gmail.com> Link: https://lkml.kernel.org/r/20180626132705.018623573@linutronix.de
130 lines
3.7 KiB
C
130 lines
3.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _linux_POSIX_TIMERS_H
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#define _linux_POSIX_TIMERS_H
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#include <linux/spinlock.h>
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#include <linux/list.h>
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#include <linux/sched.h>
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#include <linux/timex.h>
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#include <linux/alarmtimer.h>
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struct siginfo;
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struct cpu_timer_list {
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struct list_head entry;
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u64 expires, incr;
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struct task_struct *task;
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int firing;
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};
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/*
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* Bit fields within a clockid:
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*
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* The most significant 29 bits hold either a pid or a file descriptor.
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*
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* Bit 2 indicates whether a cpu clock refers to a thread or a process.
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*
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* Bits 1 and 0 give the type: PROF=0, VIRT=1, SCHED=2, or FD=3.
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*
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* A clockid is invalid if bits 2, 1, and 0 are all set.
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*/
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#define CPUCLOCK_PID(clock) ((pid_t) ~((clock) >> 3))
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#define CPUCLOCK_PERTHREAD(clock) \
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(((clock) & (clockid_t) CPUCLOCK_PERTHREAD_MASK) != 0)
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#define CPUCLOCK_PERTHREAD_MASK 4
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#define CPUCLOCK_WHICH(clock) ((clock) & (clockid_t) CPUCLOCK_CLOCK_MASK)
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#define CPUCLOCK_CLOCK_MASK 3
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#define CPUCLOCK_PROF 0
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#define CPUCLOCK_VIRT 1
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#define CPUCLOCK_SCHED 2
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#define CPUCLOCK_MAX 3
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#define CLOCKFD CPUCLOCK_MAX
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#define CLOCKFD_MASK (CPUCLOCK_PERTHREAD_MASK|CPUCLOCK_CLOCK_MASK)
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static inline clockid_t make_process_cpuclock(const unsigned int pid,
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const clockid_t clock)
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{
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return ((~pid) << 3) | clock;
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}
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static inline clockid_t make_thread_cpuclock(const unsigned int tid,
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const clockid_t clock)
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{
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return make_process_cpuclock(tid, clock | CPUCLOCK_PERTHREAD_MASK);
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}
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static inline clockid_t fd_to_clockid(const int fd)
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{
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return make_process_cpuclock((unsigned int) fd, CLOCKFD);
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}
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static inline int clockid_to_fd(const clockid_t clk)
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{
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return ~(clk >> 3);
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}
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#define REQUEUE_PENDING 1
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/**
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* struct k_itimer - POSIX.1b interval timer structure.
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* @list: List head for binding the timer to signals->posix_timers
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* @t_hash: Entry in the posix timer hash table
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* @it_lock: Lock protecting the timer
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* @kclock: Pointer to the k_clock struct handling this timer
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* @it_clock: The posix timer clock id
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* @it_id: The posix timer id for identifying the timer
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* @it_active: Marker that timer is active
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* @it_overrun: The overrun counter for pending signals
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* @it_overrun_last: The overrun at the time of the last delivered signal
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* @it_requeue_pending: Indicator that timer waits for being requeued on
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* signal delivery
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* @it_sigev_notify: The notify word of sigevent struct for signal delivery
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* @it_interval: The interval for periodic timers
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* @it_signal: Pointer to the creators signal struct
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* @it_pid: The pid of the process/task targeted by the signal
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* @it_process: The task to wakeup on clock_nanosleep (CPU timers)
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* @sigq: Pointer to preallocated sigqueue
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* @it: Union representing the various posix timer type
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* internals. Also used for rcu freeing the timer.
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*/
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struct k_itimer {
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struct list_head list;
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struct hlist_node t_hash;
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spinlock_t it_lock;
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const struct k_clock *kclock;
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clockid_t it_clock;
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timer_t it_id;
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int it_active;
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s64 it_overrun;
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s64 it_overrun_last;
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int it_requeue_pending;
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int it_sigev_notify;
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ktime_t it_interval;
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struct signal_struct *it_signal;
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union {
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struct pid *it_pid;
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struct task_struct *it_process;
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};
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struct sigqueue *sigq;
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union {
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struct {
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struct hrtimer timer;
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} real;
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struct cpu_timer_list cpu;
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struct {
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struct alarm alarmtimer;
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} alarm;
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struct rcu_head rcu;
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} it;
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};
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void run_posix_cpu_timers(struct task_struct *task);
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void posix_cpu_timers_exit(struct task_struct *task);
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void posix_cpu_timers_exit_group(struct task_struct *task);
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void set_process_cpu_timer(struct task_struct *task, unsigned int clock_idx,
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u64 *newval, u64 *oldval);
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void update_rlimit_cpu(struct task_struct *task, unsigned long rlim_new);
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void posixtimer_rearm(struct siginfo *info);
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#endif
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