iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Updates for time keeping:

Browse Source 
- Fix a couple of issues in the NTP code where user supplied values are
     neither sanity checked nor clamped to the operating range. This results
     in integer overflows and eventualy NTP getting out of sync.
 
     According to the history the sanity checks had been removed in favor of
     clamping the values, but the clamping never worked correctly under all
     circumstances. The NTP people asked to not bring the sanity checks back
     as it might break existing applications.
 
     Make the clamping work correctly and add it where it's missing
 
   - If adjtimex() sets the clock it has to trigger the hrtimer subsystem so
     it can adjust and if the clock was set into the future expire timers if
     needed. The caller should provide a bitmask to tell hrtimers which
     clocks have been adjusted. adjtimex() uses not the proper constant and
     uses CLOCK_REALTIME instead, which is 0. So hrtimers adjusts only the
     clocks, but does not check for expired timers, which might make them
     expire really late. Use the proper bitmask constant instead.
 -----BEGIN PGP SIGNATURE-----
 
 iQJHBAABCgAxFiEEQp8+kY+LLUocC4bMphj1TA10mKEFAma4wQ0THHRnbHhAbGlu
 dXRyb25peC5kZQAKCRCmGPVMDXSYoWNmEACMeq/vMoqbbhfgmTK2+XKfUarF5AX8
 61uK/rY6ysO/Qz1P+3K4j+coxhuz2t0ekjIL6htgPE0yU5JR3/VjjUpGIbBLUZfa
 aY9Ciy0OHFyTaoduyLKyiO/O7GyI6j8vMMhhNyQDaK5Zm+pIin18FqW6udg79HYh
 bDkVtCWg27M1zFd9aqRAc1EX+uFfCrSUi+1oc+E3/knDrNFUVwKCznAeDQQZii6Y
 pGmt733o7RRkABSf5T1bNOEVpbMlZowcf7zF3J57otz/lZFuwjRtTdmuG4ha3grs
 B+4FLNRZFEIEFPW0We43gAW1jLNjIL8xgZ6CMUwkUYOGQ21wmMxTOUCwg6/YMa9Y
 vBceijrICOa1EsyO28XqgRkfIvhdoNsp+c5rAN4LcQd5T7F0SoQCn9A71LXpPXgK
 ulnWjAgpt+ovD2+OFX0Ul5ySY04TgPcNVeJfnZeYxpuShlPg0GX+z0RuMl9aLbc3
 y11P0PDJiguZaoUZ8lUU2W6XA+eFEA2ZOqP+L6FZwIaDwutmXSjHR//ZkTcNg4/h
 rIbB8SFsq3BSMo3Ry2p/KMYWoZ1fF3Tm3Qp9/wpiAx1YSTJ6x8LGkHHq5c9qP5ba
 qJWi0vz8dgTGd2ta/xzglvPVWwT08rvrwACHCTcJp3Jq8uvJ27mQbTvZs6p3cFE6
 RkEBGDvEIfADew==
 =EY09
 -----END PGP SIGNATURE-----

Merge tag 'timers-urgent-2024-08-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull time keeping fixes from Thomas Gleixner:

 - Fix a couple of issues in the NTP code where user supplied values are
   neither sanity checked nor clamped to the operating range. This
   results in integer overflows and eventualy NTP getting out of sync.

   According to the history the sanity checks had been removed in favor
   of clamping the values, but the clamping never worked correctly under
   all circumstances. The NTP people asked to not bring the sanity
   checks back as it might break existing applications.

   Make the clamping work correctly and add it where it's missing

 - If adjtimex() sets the clock it has to trigger the hrtimer subsystem
   so it can adjust and if the clock was set into the future expire
   timers if needed. The caller should provide a bitmask to tell
   hrtimers which clocks have been adjusted.

   adjtimex() uses not the proper constant and uses CLOCK_REALTIME
   instead, which is 0. So hrtimers adjusts only the clocks, but does
   not check for expired timers, which might make them expire really
   late. Use the proper bitmask constant instead.

* tag 'timers-urgent-2024-08-11' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timekeeping: Fix bogus clock_was_set() invocation in do_adjtimex()
  ntp: Safeguard against time_constant overflow
  ntp: Clamp maxerror and esterror to operating range
This commit is contained in:
Linus Torvalds 2024-08-11 10:15:34 -07:00
commit 7270e931b5
2 changed files with 5 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
kernel/time/ntp.c
View File

@ -727,17 +727,16 @@ static inline void process_adjtimex_modes(const struct __kernel_timex *txc,
}
if (txc->modes & ADJ_MAXERROR)
time_maxerror = txc->maxerror;
time_maxerror = clamp(txc->maxerror, 0, NTP_PHASE_LIMIT);
if (txc->modes & ADJ_ESTERROR)
time_esterror = txc->esterror;
time_esterror = clamp(txc->esterror, 0, NTP_PHASE_LIMIT);
if (txc->modes & ADJ_TIMECONST) {
time_constant = txc->constant;
time_constant = clamp(txc->constant, 0, MAXTC);
if (!(time_status & STA_NANO))
time_constant += 4;
time_constant = min(time_constant, (long)MAXTC);
time_constant = max(time_constant, 0l);
time_constant = clamp(time_constant, 0, MAXTC);
}
if (txc->modes & ADJ_TAI &&

2
kernel/time/timekeeping.c
View File

@ -2606,7 +2606,7 @@ int do_adjtimex(struct __kernel_timex *txc)
clock_set |= timekeeping_advance(TK_ADV_FREQ);
if (clock_set)
clock_was_set(CLOCK_REALTIME);
clock_was_set(CLOCK_SET_WALL);
ntp_notify_cmos_timer();