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SubjectRe: [PATCH 17/23] y2038: time: avoid timespec usage in settimeofday()
On Fri, 8 Nov 2019, Arnd Bergmann wrote:
> -SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv,
> +SYSCALL_DEFINE2(settimeofday, struct __kernel_old_timeval __user *, tv,
> struct timezone __user *, tz)
> {
> struct timespec64 new_ts;
> - struct timeval user_tv;
> struct timezone new_tz;
>
> if (tv) {
> - if (copy_from_user(&user_tv, tv, sizeof(*tv)))
> + if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
> + get_user(new_ts.tv_nsec, &tv->tv_usec))
> return -EFAULT;

How is that supposed to be correct on a 32bit kernel?

>
> - if (!timeval_valid(&user_tv))
> + if (tv->tv_usec > USEC_PER_SEC)
> return -EINVAL;

That's incomplete:

static inline bool timeval_valid(const struct timeval *tv)
{
/* Dates before 1970 are bogus */
if (tv->tv_sec < 0)
return false;

/* Can't have more microseconds then a second */
if (tv->tv_usec < 0 || tv->tv_usec >= USEC_PER_SEC)
return false;

return true;
}


>
> - new_ts.tv_sec = user_tv.tv_sec;
> - new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
> + new_ts.tv_nsec *= NSEC_PER_USEC;
> }
> if (tz) {
> if (copy_from_user(&new_tz, tz, sizeof(*tz)))
> @@ -245,18 +244,17 @@ COMPAT_SYSCALL_DEFINE2(settimeofday, struct old_timeval32 __user *, tv,
> struct timezone __user *, tz)
> {
> struct timespec64 new_ts;
> - struct timeval user_tv;
> struct timezone new_tz;
>
> if (tv) {
> - if (compat_get_timeval(&user_tv, tv))
> + if (get_user(new_ts.tv_sec, &tv->tv_sec) ||
> + get_user(new_ts.tv_nsec, &tv->tv_usec))
> return -EFAULT;
>
> - if (!timeval_valid(&user_tv))
> + if (new_ts.tv_nsec > USEC_PER_SEC)
> return -EINVAL;

Ditto.

Thanks,

tglx

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