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author | Thomas Gleixner <tglx@linutronix.de> | 2008-02-13 08:20:43 (GMT) |
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committer | Thomas Gleixner <tglx@linutronix.de> | 2008-02-14 21:08:30 (GMT) |
commit | 5a7780e725d1bb4c3094fcc12f1c5c5faea1e988 (patch) | |
tree | 50fc5cde427f3854d0b84ba1037fef3fb4693e11 /kernel/hrtimer.c | |
parent | e760e716d47b48caf98da348368fd41b4a9b9e7e (diff) | |
download | linux-fsl-qoriq-5a7780e725d1bb4c3094fcc12f1c5c5faea1e988.tar.xz |
hrtimer: check relative timeouts for overflow
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 <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Tested-by: Frans Pop <elendil@planet.nl>
Diffstat (limited to 'kernel/hrtimer.c')
-rw-r--r-- | kernel/hrtimer.c | 37 |
1 files changed, 20 insertions, 17 deletions
diff --git a/kernel/hrtimer.c b/kernel/hrtimer.c index 3f4a57c..c2893af 100644 --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -326,6 +326,23 @@ u64 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; +} + +/* * Check, whether the timer is on the callback pending list */ static inline int hrtimer_cb_pending(const struct hrtimer *timer) @@ -682,13 +699,7 @@ u64 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 +850,7 @@ 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 +859,8 @@ 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; |