2.6.23-stable review patch. If anyone has any objections, please let us know. ------------------ From: Thomas Gleixner 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 Acked-by: Ingo Molnar Tested-by: Frans Pop Signed-off-by: Greg Kroah-Hartman --- include/linux/ktime.h | 2 ++ kernel/futex.c | 2 +- kernel/futex_compat.c | 2 +- kernel/hrtimer.c | 38 +++++++++++++++++++++----------------- kernel/posix-timers.c | 8 +++++--- 5 files changed, 30 insertions(+), 22 deletions(-) --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -289,6 +289,8 @@ static inline ktime_t ktime_add_us(const return ktime_add_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 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -2063,7 +2063,7 @@ asmlinkage long sys_futex(u32 __user *ua t = timespec_to_ktime(ts); if (cmd == FUTEX_WAIT) - t = ktime_add(ktime_get(), t); + t = ktime_add_safe(ktime_get(), t); tp = &t; } /* --- a/kernel/futex_compat.c +++ b/kernel/futex_compat.c @@ -175,7 +175,7 @@ asmlinkage long compat_sys_futex(u32 __u 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) --- a/kernel/hrtimer.c +++ b/kernel/hrtimer.c @@ -301,6 +301,24 @@ unsigned long ktime_divns(const ktime_t } #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 @@ -658,13 +676,7 @@ hrtimer_forward(struct hrtimer *timer, k */ 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; } @@ -815,7 +827,7 @@ hrtimer_start(struct hrtimer *timer, kti 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 @@ -824,16 +836,8 @@ hrtimer_start(struct hrtimer *timer, kti * 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; --- a/kernel/posix-timers.c +++ b/kernel/posix-timers.c @@ -765,9 +765,11 @@ common_timer_set(struct k_itimer *timr, /* 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; } -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/