[PATCH v3 0/2] wifi: iwlwifi: Fix GP2 to nanoseconds overflow on 32-bit

[Zhan Xusheng]

From: Zhan Xusheng <zhanxusheng@xxxxxxxxxx>

Both drivers multiply a u32 GP2 microsecond timestamp by NSEC_PER_USEC
without widening first.  On 32-bit the product truncates for any GP2
value above 4.295 s, and the truncated value is fed back into the
wraparound detector, which records a false GP2 wraparound and adds
about 71.6 minutes to every later PHC timestamp, cumulatively.

Six sites, three per driver:

  mvm/ptp.c   scale_update_gp2 in iwl_mvm_ptp_get_adj_time()
  mvm/ptp.c   gp2 in iwl_mvm_ptp_adjfine()
  mvm/rxmq.c  gp2_on_air_rise in iwl_mvm_rx_he()
  mld/ptp.c   scale_update_gp2 in iwl_mld_ptp_get_adj_time()
  mld/ptp.c   gp2 in iwl_mld_ptp_adjfine()
  mld/rx.c    gp2_on_air_rise in iwl_mld_rx_fill_status()

iwl_mvm_ptp_gettime() holds its GP2 read in a u64 and
iwl_mld_phc_get_crosstimestamp() casts, so those two are already right.

Changes since v2:

 - mvm: added scale_update_gp2 and the adjfine() site.  v2 only
   covered mvm/rxmq.c.
 - mld: added the iwl_mld_rx_fill_status() site.  v2 only covered
   mld/ptp.c while claiming parity with the mvm fix.  Reported by the
   netdev Sashiko review bot.
 - mld: iwl_mld_ptp_get_crosstimestamp() in the v2 changelog does not
   exist; the function is iwl_mld_phc_get_crosstimestamp().
 - both: state the wraparound consequence with the numbers.

No Cc: stable.  The affected intersection is 32-bit plus iwlwifi plus
PTP, so that call belongs to the maintainers.

v2: https://patch.msgid.link/20261001050103.860584-1-zhanxusheng@xxxxxxxxxx

Zhan Xusheng (2):
  wifi: iwlwifi: mvm: Fix GP2 to nanoseconds overflow on 32-bit
  wifi: iwlwifi: mld: Fix GP2 to nanoseconds overflow on 32-bit

 drivers/net/wireless/intel/iwlwifi/mld/ptp.c  | 5 +++--
 drivers/net/wireless/intel/iwlwifi/mld/rx.c   | 2 +-
 drivers/net/wireless/intel/iwlwifi/mvm/ptp.c  | 5 +++--
 drivers/net/wireless/intel/iwlwifi/mvm/rxmq.c | 4 +++-
 4 files changed, 10 insertions(+), 6 deletions(-)


base-commit: d6d3455d8751854e0d1820f14184682e23ac4475
-- 
2.43.0