RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

Description of problem:


Version-Release number of selected component (if applicable):

bash-4.1.2-9.el6_2

How reproducible:

40%


Steps to Reproduce:

In some complex situation, the bash itself will hang.
Check the Trace of stack, we can found there is a bug in its signal handler.
It calls some not-async-signal-safe functions such as malloc in the signal handler function.

(gdb) bt
#0  __lll_lock_wait_private () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:97
#1  0x0000003c8147bed5 in _L_lock_9323 () from /lib64/libc.so.6
#2  0x0000003c814797c6 in __libc_malloc (bytes=259870211712) at malloc.c:3657
#3  0x0000000000465ef3 in xmalloc (bytes=16) at xmalloc.c:112
#4  0x000000000041de9e in save_token_state () at ./parse.y:1737
#5  0x0000000000450709 in run_pending_traps () at trap.c:337
#6  0x00000000004508fd in trap_handler (sig=12) at trap.c:401
#7  <signal handler called>
#8  _int_malloc (av=0x3c8178be80, bytes=<value optimized out>) at malloc.c:4706


Patch within 4.1.2-9 only fixed the handler of SIGCHLD.
* Thu Apr 19 2012 Roman Rakus <rrakus> - 4.1.2-9
- Don't call malloc in signal handler
  Resolves: #800473

check the following url for a testcase
http://lists.gnu.org/archive/html/bug-bash/2012-10/msg00039.html

This request was not resolved in time for the current release.
Red Hat invites you to ask your support representative to
propose this request, if still desired, for consideration in
the next release of Red Hat Enterprise Linux.

This request was evaluated by Red Hat Product Management for
inclusion in the current release of Red Hat Enterprise Linux.
Because the affected component is not scheduled to be updated
in the current release, Red Hat is unable to address this
request at this time.

Red Hat invites you to ask your support representative to
propose this request, if appropriate, in the next release of
Red Hat Enterprise Linux.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2016-0800.html