From 59a37f8baeb2c9d97f316584c90892d18bf846d4 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 17 Jun 2016 16:58:26 +0200 Subject: [PATCH] blktrace: avoid using timespec 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 Signed-off-by: Jens Axboe --- 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 03b0dd98ff0e..bedb84d168d1 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); -- 2.20.1