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[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>
This commit is contained in:
Thomas Gleixner 2006-09-06 00:03:42 -07:00 committed by Linus Torvalds
parent fe2bbc4832
commit 96dd7421a0
1 changed files with 6 additions and 1 deletions
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7
include/linux/ktime.h
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@ -56,7 +56,8 @@ typedef union {
#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 @@ typedef union {
*/
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 };
}