diff options
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 12 | ||||
| -rw-r--r-- | kernel/itimer.c | 66 |
2 files changed, 78 insertions, 0 deletions
diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 21272e4..495858b 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -176,6 +176,18 @@ Who: Richard Knutsson <ricknu-0@student.ltu.se> and Greg Kroah-Hartman <gregkh@s --------------------------- +What: Usage of invalid timevals in setitimer +When: March 2007 +Why: POSIX requires to validate timevals in the setitimer call. This + was never done by Linux. The invalid (e.g. negative timevals) were + silently converted to more or less random timeouts and intervals. + Until the removal a per boot limited number of warnings is printed + and the timevals are sanitized. + +Who: Thomas Gleixner <tglx@linutronix.de> + +--------------------------- + What: I2C interface of the it87 driver When: January 2007 Why: The ISA interface is faster and should be always available. The I2C diff --git a/kernel/itimer.c b/kernel/itimer.c index a2dc3759..680e6b7 100644 --- a/kernel/itimer.c +++ b/kernel/itimer.c @@ -143,6 +143,60 @@ int it_real_fn(void *data) return HRTIMER_NORESTART; } +/* + * We do not care about correctness. We just sanitize the values so + * the ktime_t operations which expect normalized values do not + * break. This converts negative values to long timeouts similar to + * the code in kernel versions < 2.6.16 + * + * Print a limited number of warning messages when an invalid timeval + * is detected. + */ +static void fixup_timeval(struct timeval *tv, int interval) +{ + static int warnlimit = 10; + unsigned long tmp; + + if (warnlimit > 0) { + warnlimit--; + printk(KERN_WARNING + "setitimer: %s (pid = %d) provided " + "invalid timeval %s: tv_sec = %ld tv_usec = %ld\n", + current->comm, current->pid, + interval ? "it_interval" : "it_value", + tv->tv_sec, (long) tv->tv_usec); + } + + tmp = tv->tv_usec; + if (tmp >= USEC_PER_SEC) { + tv->tv_usec = tmp % USEC_PER_SEC; + tv->tv_sec += tmp / USEC_PER_SEC; + } + + tmp = tv->tv_sec; + if (tmp > LONG_MAX) + tv->tv_sec = LONG_MAX; +} + +/* + * Returns true if the timeval is in canonical form + */ +#define timeval_valid(t) \ + (((t)->tv_sec >= 0) && (((unsigned long) (t)->tv_usec) < USEC_PER_SEC)) + +/* + * Check for invalid timevals, sanitize them and print a limited + * number of warnings. + */ +static void check_itimerval(struct itimerval *value) { + + if (unlikely(!timeval_valid(&value->it_value))) + fixup_timeval(&value->it_value, 0); + + if (unlikely(!timeval_valid(&value->it_interval))) + fixup_timeval(&value->it_interval, 1); +} + int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) { struct task_struct *tsk = current; @@ -150,6 +204,18 @@ int do_setitimer(int which, struct itimerval *value, struct itimerval *ovalue) ktime_t expires; cputime_t cval, cinterval, nval, ninterval; + /* + * Validate the timevals in value. + * + * Note: Although the spec requires that invalid values shall + * return -EINVAL, we just fixup the value and print a limited + * number of warnings in order not to break users of this + * historical misfeature. + * + * Scheduled for replacement in March 2007 + */ + check_itimerval(value); + switch (which) { case ITIMER_REAL: again: |