commit 85d1617924607c1311962546bb55367b9edb4ca6
Author: Thomas Gleixner <[EMAIL PROTECTED]>
Date: Wed Feb 20 01:03:00 2008 +0100
hrtimer: check relative timeouts for overflow
commit: 5a7780e725d1bb4c3094fcc12f1c5c5faea1e988
Various user space callers ask for relative timeouts. While we fixed
that overflow issue in hrtimer_start(), the sites which convert
relative user space values to absolute timeouts themself were uncovered.
Instead of putting overflow checks into each place add a function
which does the sanity checking and convert all affected callers to use
it.
Thanks to Frans Pop, who reported the problem and tested the fixes.
Signed-off-by: Thomas Gleixner <[EMAIL PROTECTED]>
Acked-by: Ingo Molnar <[EMAIL PROTECTED]>
Tested-by: Frans Pop <[EMAIL PROTECTED]>
Signed-off-by: Greg Kroah-Hartman <[EMAIL PROTECTED]>
diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index a6ddec1..816cf4e 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -310,6 +310,8 @@ static inline ktime_t ktime_sub_us(const ktime_t kt, const
u64 usec)
return ktime_sub_ns(kt, usec * 1000);
}
+extern ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs);
+
/*
* The resolution of the clocks. The resolution value is returned in
* the clock_getres() system call to give application programmers an
diff --git a/kernel/futex.c b/kernel/futex.c
index db9824d..55d78b5 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -2094,7 +2094,7 @@ asmlinkage long sys_futex(u32 __user *uaddr, int op, u32
val,
t = timespec_to_ktime(ts);
if (cmd == FUTEX_WAIT)
- t = ktime_add(ktime_get(), t);
+ t = ktime_add_safe(ktime_get(), t);
tp = &t;
}
/*
diff --git a/kernel/futex_compat.c b/kernel/futex_compat.c
index 0a43def..8682c79 100644
--- a/kernel/futex_compat.c
+++ b/kernel/futex_compat.c
@@ -175,7 +175,7 @@ asmlinkage long compat_sys_futex(u32 __user *uaddr, int op,
u32 val,
t = timespec_to_ktime(ts);
if (cmd == FUTEX_WAIT)
- t = ktime_add(ktime_get(), t);
+ t = ktime_add_safe(ktime_get(), t);
tp = &t;
}
if (cmd == FUTEX_REQUEUE || cmd == FUTEX_CMP_REQUEUE)
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c
index fac8076..2ed8002 100644
--- a/kernel/hrtimer.c
+++ b/kernel/hrtimer.c
@@ -325,6 +325,24 @@ unsigned long ktime_divns(const ktime_t kt, s64 div)
}
#endif /* BITS_PER_LONG >= 64 */
+/*
+ * Add two ktime values and do a safety check for overflow:
+ */
+
+ktime_t ktime_add_safe(const ktime_t lhs, const ktime_t rhs)
+{
+ ktime_t res = ktime_add(lhs, rhs);
+
+ /*
+ * We use KTIME_SEC_MAX here, the maximum timeout which we can
+ * return to user space in a timespec:
+ */
+ if (res.tv64 < 0 || res.tv64 < lhs.tv64 || res.tv64 < rhs.tv64)
+ res = ktime_set(KTIME_SEC_MAX, 0);
+
+ return res;
+}
+
/* High resolution timer related functions */
#ifdef CONFIG_HIGH_RES_TIMERS
@@ -682,13 +700,7 @@ hrtimer_forward(struct hrtimer *timer, ktime_t now,
ktime_t interval)
*/
orun++;
}
- timer->expires = ktime_add(timer->expires, interval);
- /*
- * Make sure, that the result did not wrap with a very large
- * interval.
- */
- if (timer->expires.tv64 < 0)
- timer->expires = ktime_set(KTIME_SEC_MAX, 0);
+ timer->expires = ktime_add_safe(timer->expires, interval);
return orun;
}
@@ -839,7 +851,7 @@ hrtimer_start(struct hrtimer *timer, ktime_t tim, const
enum hrtimer_mode mode)
new_base = switch_hrtimer_base(timer, base);
if (mode == HRTIMER_MODE_REL) {
- tim = ktime_add(tim, new_base->get_time());
+ tim = ktime_add_safe(tim, new_base->get_time());
/*
* CONFIG_TIME_LOW_RES is a temporary way for architectures
* to signal that they simply return xtime in
@@ -848,16 +860,8 @@ hrtimer_start(struct hrtimer *timer, ktime_t tim, const
enum hrtimer_mode mode)
* timeouts. This will go away with the GTOD framework.
*/
#ifdef CONFIG_TIME_LOW_RES
- tim = ktime_add(tim, base->resolution);
+ tim = ktime_add_safe(tim, base->resolution);
#endif
- /*
- * Careful here: User space might have asked for a
- * very long sleep, so the add above might result in a
- * negative number, which enqueues the timer in front
- * of the queue.
- */
- if (tim.tv64 < 0)
- tim.tv64 = KTIME_MAX;
}
timer->expires = tim;
diff --git a/kernel/posix-timers.c b/kernel/posix-timers.c
index 6cf6714..9076432 100644
--- a/kernel/posix-timers.c
+++ b/kernel/posix-timers.c
@@ -766,9 +766,11 @@ common_timer_set(struct k_itimer *timr, int flags,
/* SIGEV_NONE timers are not queued ! See common_timer_get */
if (((timr->it_sigev_notify & ~SIGEV_THREAD_ID) == SIGEV_NONE)) {
/* Setup correct expiry time for relative timers */
- if (mode == HRTIMER_MODE_REL)
- timer->expires = ktime_add(timer->expires,
- timer->base->get_time());
+ if (mode == HRTIMER_MODE_REL) {
+ timer->expires =
+ ktime_add_safe(timer->expires,
+ timer->base->get_time());
+ }
return 0;
}
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