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-rw-r--r--Documentation/feature-removal-schedule.txt12
-rw-r--r--kernel/itimer.c66
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:
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