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| author | Thomas Gleixner <tglx@linutronix.de> | 2006-09-06 00:03:42 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-09-06 11:00:02 -0700 |
| commit | 96dd7421a06a5bc6eb731323b95efcb2fd864854 (patch) | |
| tree | a450951e439f897ee92ba6b068efb77c0edc6a1a /include/linux/ktime.h | |
| parent | fe2bbc4832659b7ffc867cac03e0a92ae81e11e4 (diff) | |
| download | lwn-96dd7421a06a5bc6eb731323b95efcb2fd864854.tar.gz lwn-96dd7421a06a5bc6eb731323b95efcb2fd864854.zip | |
[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>
Diffstat (limited to 'include/linux/ktime.h')
| -rw-r--r-- | include/linux/ktime.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/include/linux/ktime.h b/include/linux/ktime.h index ed3396dcc4f7..84eeecd60a02 100644 --- a/include/linux/ktime.h +++ b/include/linux/ktime.h @@ -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 }; } |