Merge ~bryce/ubuntu/+source/bash:ubuntu/bionic-devel into ubuntu/+source/bash:ubuntu/bionic-devel

[Bryce Harrington]

Backport of an upstream fix to a cpu hang when waiting on background tasks.

PPA available for testing is at
https://launchpad.net/~bryce/+archive/ubuntu/bash-sru-19-010-1

I was not able to reproduce the hang myself, but apparently it can take days or weeks to reproduce. However, the fix was taken upstream and looks clearly correct to me. I'm confident given enough run time it would reproduce. It may be difficult to positively test for the bug's absence however.

I'm assuming that the target branch for this should be ubuntu/cosmic-devel; I couldn't find documentation to this effect however it seems to be what others are targeting to. Let me know if it's wrong.

I'm unclear if any tags are needed for SRU bugs but am gathering that none are. Again, let me know if otherwise.

[Andreas Hasenack (ahasenack)]

Same comments as with the cosmic MP at https://code.launchpad.net/~bryce/ubuntu/+source/bash/+git/bash/+merge/368573.
- add dep3
- don't use -proposed

[Bryce Harrington (bryce)]

Updated; same changes as the other branch. Thanks again.

[Andreas Hasenack (ahasenack)]

+1

review: Approve

[Andreas Hasenack (ahasenack)]

Pushing upload tag, and then you can dput:

$ git push pkg upload/4.4.18-2ubuntu1.2
Enumerating objects: 16, done.
Counting objects: 100% (16/16), done.
Delta compression using up to 2 threads
Compressing objects: 100% (11/11), done.
Writing objects: 100% (11/11), 2.72 KiB | 558.00 KiB/s, done.
Total 11 (delta 7), reused 0 (delta 0)
To ssh://git.launchpad.net/~usd-import-team/ubuntu/+source/bash
 * [new tag] upload/4.4.18-2ubuntu1.2 -> upload/4.4.18-2ubuntu1.2

[Bryce Harrington (bryce)]

Thanks, pushed.

diff --git a/debian/changelog b/debian/changelog
index 25c90d5..454a4e3 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,10 @@
+bash (4.4.18-2ubuntu1.2) bionic; urgency=medium
+
+  * d/p/bash44-020.diff: Add fix for hang on 'wait' statement
+    (LP: #1822776)
+
+ -- Bryce Harrington <[e-mail]>  Thu, 06 Jun 2019 15:28:15 -0700
+
 bash (4.4.18-2ubuntu1.1) bionic; urgency=medium
 
   * Resurrect "Set the default path to comply with Debian policy" in
diff --git a/debian/patches/bash44-020.diff b/debian/patches/bash44-020.diff
new file mode 100644
index 0000000..340d085
--- /dev/null
+++ b/debian/patches/bash44-020.diff
@@ -0,0 +1,144 @@
+			     BASH PATCH REPORT
+			     =================
+
+Bash-Release:	4.4
+Patch-ID:	bash44-020
+
+Bug-Reported-by:	Graham Northup <[e-mail]>
+Bug-Reference-ID:	<[e-mail]>
+Bug-Reference-URL:	http://lists.gnu.org/archive/html/bug-bash/2017-02/msg00025.html
+
+Bug-Description:
+
+In circumstances involving long-running scripts that create and reap many
+processes, it is possible for the hash table bash uses to store exit
+statuses from asynchronous processes to develop loops. This patch fixes
+the loop causes and adds code to detect any future loops.
+
+Origin: upstream, https://ftp.gnu.org/gnu/bash/bash-4.4-patches/bash44-020
+Bug-Ubuntu: https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1822776
+Last-Update: 2019-06-10
+
+diff --git a/jobs.c b/jobs.c
+index fc96603..2684632 100644
+--- a/jobs.c
++++ b/jobs.c
+@@ -812,8 +812,22 @@ bgp_add (pid, status)
+   ps_index_t *bucket, psi;
+   struct pidstat *ps;
+ 
+-  bucket = pshash_getbucket (pid);
+-  psi = bgp_getindex ();
++  /* bucket == existing chain of pids hashing to same value
++     psi = where were going to put this pid/status */
++
++  bucket = pshash_getbucket (pid);	/* index into pidstat_table */
++  psi = bgp_getindex ();		/* bgpids.head, index into storage */
++
++  /* XXX - what if psi == *bucket? */
++  if (psi == *bucket)
++    {
++#ifdef DEBUG
++      internal_warning ("hashed pid %d (pid %d) collides with bgpids.head, skipping", psi, pid);
++#endif
++      bgpids.storage[psi].pid = NO_PID;		/* make sure */
++      psi = bgp_getindex ();			/* skip to next one */
++    }
++
+   ps = &bgpids.storage[psi];
+ 
+   ps->pid = pid;
+@@ -841,32 +855,47 @@ pshash_delindex (psi)
+      ps_index_t psi;
+ {
+   struct pidstat *ps;
++  ps_index_t *bucket;
+ 
+   ps = &bgpids.storage[psi];
+   if (ps->pid == NO_PID)
+     return;
+ 
+-  if (ps->bucket_next != NO_PID)
++  if (ps->bucket_next != NO_PIDSTAT)
+     bgpids.storage[ps->bucket_next].bucket_prev = ps->bucket_prev;
+-  if (ps->bucket_prev != NO_PID)
++  if (ps->bucket_prev != NO_PIDSTAT)
+     bgpids.storage[ps->bucket_prev].bucket_next = ps->bucket_next;
+   else
+-    *(pshash_getbucket (ps->pid)) = ps->bucket_next;
++    {
++      bucket = pshash_getbucket (ps->pid);
++      *bucket = ps->bucket_next;	/* deleting chain head in hash table */
++    }
++
++  /* clear out this cell, just in case */
++  ps->pid = NO_PID;
++  ps->bucket_next = ps->bucket_prev = NO_PIDSTAT;
+ }
+ 
+ static int
+ bgp_delete (pid)
+      pid_t pid;
+ {
+-  ps_index_t psi;
++  ps_index_t psi, orig_psi;
+ 
+   if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0)
+     return 0;
+ 
+   /* Search chain using hash to find bucket in pidstat_table */
+-  for (psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next)
+-    if (bgpids.storage[psi].pid == pid)
+-      break;
++  for (orig_psi = psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next)
++    {
++      if (bgpids.storage[psi].pid == pid)
++	break;
++      if (orig_psi == bgpids.storage[psi].bucket_next)	/* catch reported bug */
++	{
++	  internal_warning ("bgp_delete: LOOP: psi (%d) == storage[psi].bucket_next", psi);
++	  return 0;
++	}
++    }
+ 
+   if (psi == NO_PIDSTAT)
+     return 0;		/* not found */
+@@ -904,15 +933,22 @@ static int
+ bgp_search (pid)
+      pid_t pid;
+ {
+-  ps_index_t psi;
++  ps_index_t psi, orig_psi;
+ 
+   if (bgpids.storage == 0 || bgpids.nalloc == 0 || bgpids.npid == 0)
+     return -1;
+ 
+   /* Search chain using hash to find bucket in pidstat_table */
+-  for (psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next)
+-    if (bgpids.storage[psi].pid == pid)
+-      return (bgpids.storage[psi].status);
++  for (orig_psi = psi = *(pshash_getbucket (pid)); psi != NO_PIDSTAT; psi = bgpids.storage[psi].bucket_next)
++    {
++      if (bgpids.storage[psi].pid == pid)
++	return (bgpids.storage[psi].status);
++      if (orig_psi == bgpids.storage[psi].bucket_next)	/* catch reported bug */
++	{
++	  internal_warning ("bgp_search: LOOP: psi (%d) == storage[psi].bucket_next", psi);
++	  return -1;
++	}
++    }
+ 
+   return -1;
+ }
+diff --git a/patchlevel.h b/patchlevel.h
+index a711c49..4a65dc0 100644
+--- a/patchlevel.h
++++ b/patchlevel.h
+@@ -25,6 +25,6 @@
+    regexp `^#define[ 	]*PATCHLEVEL', since that's what support/mkversion.sh
+    looks for to find the patch level (for the sccs version string). */
+ 
+-#define PATCHLEVEL 19
++#define PATCHLEVEL 20
+ 
+ #endif /* _PATCHLEVEL_H_ */
diff --git a/debian/patches/series b/debian/patches/series
index ee570e7..dab8a2a 100644
--- a/debian/patches/series
+++ b/debian/patches/series
@@ -22,3 +22,4 @@ bzero.diff
 man-macro-warnings.diff
 po-de-fix.diff
 man-vx-opts.diff
+bash44-020.diff