Jens,
You want to take this, or do you want me to?
-- Steve
On Fri, 17 Jun 2016 16:58:26 +0200
Arnd Bergmann <arnd@xxxxxxxx> wrote:
> The blktrace code stores the current time in a 32-bit word in its
> user interface. This is a bad idea because 32-bit seconds overflow
> at some point.
>
> We probably have until 2106 before this one overflows, as it seems
> to use an 'unsigned' variable, but we should confirm that user
> space treats it the same way.
>
> Aside from this, we want to stop using 'struct timespec' here,
> so I'm adding a comment about the overflow and change the code
> to use timespec64 instead to make the loss of range more obvious.
>
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> kernel/trace/blktrace.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/kernel/trace/blktrace.c b/kernel/trace/blktrace.c
> index ef86b965ade3..b0816e4a61a5 100644
> --- a/kernel/trace/blktrace.c
> +++ b/kernel/trace/blktrace.c
> @@ -127,12 +127,13 @@ static void trace_note_tsk(struct task_struct *tsk)
>
> static void trace_note_time(struct blk_trace *bt)
> {
> - struct timespec now;
> + struct timespec64 now;
> unsigned long flags;
> u32 words[2];
>
> - getnstimeofday(&now);
> - words[0] = now.tv_sec;
> + /* need to check user space to see if this breaks in y2038 or y2106 */
> + ktime_get_real_ts64(&now);
> + words[0] = (u32)now.tv_sec;
> words[1] = now.tv_nsec;
>
> local_irq_save(flags);
--
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