[PATCH v5 1/2] posix-clock: Fix missing timespec64 check in pc_clock_settime()

[Jinjie Ruan]

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.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: 0606f422b453 ("posix clocks: Introduce dynamic clocks")
Suggested-by: Andrew Lunn <andrew@xxxxxxx>
Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Jinjie Ruan <ruanjinjie@xxxxxxxxxx>
---
v5:
- Update the commit message.
- Use timespec64_valid_strict() instead of timespec64_valid()
  as Thomas suggested.
- Add fix tag.
v4:
- Check it in pc_clock_settime().
- Update the commit message.
v3:
- Adjust to check in more higher layer clock_settime().
- Remove the NULL check.
- Update the commit message and subject.
v2:
- Adjust to check in ptp_clock_settime().
---
 kernel/time/posix-clock.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/posix-clock.c b/kernel/time/posix-clock.c
index c2f3d0c490d5..316a4e8c97d3 100644
--- a/kernel/time/posix-clock.c
+++ b/kernel/time/posix-clock.c
@@ -318,6 +318,9 @@ static int pc_clock_settime(clockid_t id, const struct timespec64 *ts)
 		goto out;
 	}
 
+	if (!timespec64_valid_strict(ts))
+		return -EINVAL;
+
 	if (cd.clk->ops.clock_settime)
 		err = cd.clk->ops.clock_settime(cd.clk, ts);
 	else
-- 
2.34.1