timekeeping: Zero initialize system_counterval when querying time from phc drivers

Most drivers only populate the fields cycles and cs_id of system_counterval
in their get_time_fn() callback for get_device_system_crosststamp(), unless
they explicitly provide nanosecond values.

When the use_nsecs field was added to struct system_counterval, most
drivers did not care.  Clock sources other than CSID_GENERIC could then get
converted in convert_base_to_cs() based on an uninitialized use_nsecs field,
which usually results in -EINVAL during the following range check.

Pass in a fully zero initialized system_counterval_t to cure that.

Fixes: 6b2e29977518 ("timekeeping: Provide infrastructure for converting to/from a base clock")
Signed-off-by: Markus Blöchl <markus@blochl.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: John Stultz <jstultz@google.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250720-timekeeping_uninit_crossts-v2-1-f513c885b7c2@blochl.de

diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index a009c91f7b05fcb433073862a1b1a3de0345bffe..83c65f3afccaacff7a2e53e62f32657c201fbc8c 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -1256,7 +1256,7 @@ int get_device_system_crosststamp(int (*get_time_fn)
                                  struct system_time_snapshot *history_begin,
                                  struct system_device_crosststamp *xtstamp)
 {
-       struct system_counterval_t system_counterval;
+       struct system_counterval_t system_counterval = {};
        struct timekeeper *tk = &tk_core.timekeeper;
        u64 cycles, now, interval_start;
        unsigned int clock_was_set_seq = 0;