Experimental Physics and
Industrial Control System

Dirk Zimoch via Core-talk <core-talk at aps.anl.gov> · Wed, 16 Jun 2021 07:08:59 -0000

Public bug reported:

If epicsAtomicCmpAndSwapIntT() in callbackInit() fails for some reason
(e.g. because of bug #1932118), the callback queues never get
initialized (and callback threads never get started). Nevertheless,
callbackRequest() will use these uninitialized queues (and an
uninitialized event semaphore) without checking, resulting in strange
message from a spinLock in the uninitialized queue:

0x132f380 (timerQueue): epicsSpinLock(0x1fda0b79): Deadlock.
Recursive lock, missed unlock or block when locked.Thread timerQueue (0x132f380) can't proceed, suspending.

A patch is attached.

** Affects: epics-base
     Importance: Undecided
         Status: New

** Patch added: "patch"
   https://bugs.launchpad.net/bugs/1932120/+attachment/5504984/+files/callback.patch

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https://bugs.launchpad.net/bugs/1932120

Title:
  callbackRequest potentially accesses uninitialized memory

Status in EPICS Base:
  New

Bug description:
  If epicsAtomicCmpAndSwapIntT() in callbackInit() fails for some reason
  (e.g. because of bug #1932118), the callback queues never get
  initialized (and callback threads never get started). Nevertheless,
  callbackRequest() will use these uninitialized queues (and an
  uninitialized event semaphore) without checking, resulting in strange
  message from a spinLock in the uninitialized queue:

  0x132f380 (timerQueue): epicsSpinLock(0x1fda0b79): Deadlock.
  Recursive lock, missed unlock or block when locked.Thread timerQueue (0x132f380) can't proceed, suspending.

  A patch is attached.

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System