[PATCH] prevent timespec/timeval to ktime_t overflow
Frank v. Waveren pointed out that on 64bit machines the timespec to
ktime_t conversion might overflow. This is also true for timeval to
ktime_t conversions. This breaks a "sleep inf" on 64bit machines.
While a timespec/timeval with tx.sec = MAX_LONG is valid by specification
the internal representation of ktime_t is based on nanoseconds. The
conversion of seconds to nanoseconds overflows for seconds values >=
(MAX_LONG / NSEC_PER_SEC).
Check the seconds argument to the conversion and limit it to the maximum
time which can be represented by ktime_t.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frank v Waveren <fvw@var.cx>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/include/linux/ktime.h b/include/linux/ktime.h
index ed3396d..84eeecd 100644
--- a/include/linux/ktime.h
+++ b/include/linux/ktime.h
@@ -56,7 +56,8 @@
#endif
} ktime_t;
-#define KTIME_MAX (~((u64)1 << 63))
+#define KTIME_MAX ((s64)~((u64)1 << 63))
+#define KTIME_SEC_MAX (KTIME_MAX / NSEC_PER_SEC)
/*
* ktime_t definitions when using the 64-bit scalar representation:
@@ -73,6 +74,10 @@
*/
static inline ktime_t ktime_set(const long secs, const unsigned long nsecs)
{
+#if (BITS_PER_LONG == 64)
+ if (unlikely(secs >= KTIME_SEC_MAX))
+ return (ktime_t){ .tv64 = KTIME_MAX };
+#endif
return (ktime_t) { .tv64 = (s64)secs * NSEC_PER_SEC + (s64)nsecs };
}