Resolved vulnerability in Linux kernel's posix-clock

CVE-2024-50195

What is CVE-2024-50195?

In the Linux kernel, the following vulnerability has been resolved:

posix-clock: Fix missing timespec64 check in pc_clock_settime()

As Andrew pointed out, it will make sense that the PTP core checked timespec64 struct's tv_sec and tv_nsec range before calling ptp->info->settime64().

As the man manual of clock_settime() said, if tp.tv_sec is negative or tp.tv_nsec is outside the range [0..999,999,999], it should return EINVAL, which include dynamic clocks which handles PTP clock, and the condition is consistent with timespec64_valid(). As Thomas suggested, timespec64_valid() only check the timespec is valid, but not ensure that the time is in a valid range, so check it ahead using timespec64_valid_strict() in pc_clock_settime() and return -EINVAL if not valid.

There are some drivers that use tp->tv_sec and tp->tv_nsec directly to write registers without validity checks and assume that the higher layer has checked it, which is dangerous and will benefit from this, such as hclge_ptp_settime(), igb_ptp_settime_i210(), _rcar_gen4_ptp_settime(), and some drivers can remove the checks of itself.

References