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A single fix for the PTP systemcounter mechanism:

Browse Source 
The rework of this mechanism added a 'use_nsec' member to struct
   system_counterval. get_device_system_crosststamp() instantiates that
   struct on the stack and hands a pointer to the driver callback.
 
   Only the drivers which set use_nsec to true, initialize that field, but
   all others ignore it. As get_device_system_crosststamp() does not
   initialize the struct, the use_nsec field contains random stack content
   in those cases. That causes a miscalulation usually resulting in a
   failing range check in the best case.
 
   Initialize the structure before handing it to the drivers to cure that.
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Merge tag 'timers-urgent-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull timer fix from Thomas Gleixner:
 "A single fix for the PTP systemcounter mechanism:

  The rework of this mechanism added a 'use_nsec' member to struct
  system_counterval. get_device_system_crosststamp() instantiates that
  struct on the stack and hands a pointer to the driver callback.

  Only the drivers which set use_nsec to true, initialize that field,
  but all others ignore it. As get_device_system_crosststamp() does not
  initialize the struct, the use_nsec field contains random stack
  content in those cases. That causes a miscalulation usually resulting
  in a failing range check in the best case.

  Initialize the structure before handing it to the drivers to cure
  that"

* tag 'timers-urgent-2025-07-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timekeeping: Zero initialize system_counterval when querying time from phc drivers
This commit is contained in:
Linus Torvalds 2025-07-27 09:31:32 -07:00
commit b711733e89
1 changed files with 1 additions and 1 deletions
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2
kernel/time/timekeeping.c
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@ -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;