svn commit: r368322 - stable/12/sys/kern

[Kyle Evans]

Author: kevans
Date: Fri Dec  4 02:19:45 2020
New Revision: 368322
URL: https://svnweb.freebsd.org/changeset/base/368322

Log:
  MFC r367944: cpuset_setproc: use the appropriate parent for new anon. sets
  
  As far as I can tell, this has been the case since initially committed in
  2008.  cpuset_setproc is the executor of cpuset reassignment; note this
  excerpt from the description:
  
  * 1) Set is non-null.  This reparents all anonymous sets to the provided
  *    set and replaces all non-anonymous td_cpusets with the provided set.
  
  However, reviewing cpuset_setproc_setthread() for some jail related work
  unearthed the error: if tdset was not anonymous, we were replacing it with
  `set`. If it was anonymous, then we'd rebase it onto `set` (i.e. copy the
  thread's mask over and AND it with `set`) but give the new anonymous set
  the original tdset as the parent (i.e. the base of the set we're supposed to
  be leaving behind).
  
  The primary visible consequences were that:
  
  1.) cpuset_getid() following such assignment returns the wrong result, the
      setid that we left behind rather than the one we joined.
  2.) When a process attached to the jail, the base set of any anonymous
      threads was a set outside of the jail.
  
  This was initially bundled in D27298, but it's a minor fix that's fairly
  easy to verify the correctness of.
  
  A test is included in D27307 ("badparent"), which demonstrates the issue
  with, effectively:
  
  osetid = cpuset_getid()
  newsetid = cpuset()
  cpuset_setaffinity(thread)
  cpuset_setid(osetid)
  cpuset_getid(thread) -> observe that it matches newsetid instead of osetid.

Modified:
  stable/12/sys/kern/kern_cpuset.c
Directory Properties:
  stable/12/   (props changed)

Modified: stable/12/sys/kern/kern_cpuset.c
==============================================================================
--- stable/12/sys/kern/kern_cpuset.c	Fri Dec  4 02:18:40 2020	(r368321)
+++ stable/12/sys/kern/kern_cpuset.c	Fri Dec  4 02:19:45 2020	(r368322)
@@ -1095,7 +1095,7 @@ cpuset_setproc_setthread(struct cpuset *tdset, struct 
 	if (error)
 		return (error);
 
-	return cpuset_shadow(tdset, nsetp, &mask, &domain, freelist,
+	return cpuset_shadow(set, nsetp, &mask, &domain, freelist,
 	    domainlist);
 }