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Bug 1633755

Summary: emacs crashes on very specific C code input
Product: Red Hat Enterprise Linux 7 Reporter: Joe Wright <jwright>
Component: emacsAssignee: Lukáš Nykrýn <lnykryn>
Status: CLOSED WONTFIX QA Contact: qe-baseos-daemons
Severity: low Docs Contact:
Priority: low    
Version: 7.5CC: alanm, jwright, kwalker, mjbauer
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2020-11-11 21:48:46 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1630908, 1643104, 1719445    

Description Joe Wright 2018-09-27 16:17:53 UTC
Description of problem:
- emacs crashes in C/l abbrev mode when attempting to paste a comment line that does not end in a carriage return at the very end of the file.

Version-Release number of selected component (if applicable):
- emacs-24.3-20.el7_4.x86_64

How reproducible:


Steps to Reproduce:
1. Open any .c file in emacs.  (This should put you in C/l Abbrev mode.)
2. Go to the bottom of the file.
3. Type any valid comment line as the whole of the last line of the file, that is, it must begin with '/*', have anywhere from zero to N characters, and end with '*/'.  Do *not* press "return".
4. Go to the beginning of the line and type ^k, to kill the line and copy it into the paste buffer.
5. Paste it back with ^y.

Emacs should crash immediately and dump core.

This happens only in C/l Abbrev mode of the modes I've tried.  (In particular, it does not trigger in any of Fundamental, Lisp Interaction, or Perl mode.


Actual results:
- crash and core dump

Expected results:
- no crash

Additional info:
- also reproduced in version emacs-24.3-21.el7.x86_64

Comment 2 Joe Wright 2018-10-01 13:26:47 UTC
Reproducer Steps:

* Start emacs
^X^F
Find file: ~/foo.c

(It's actually easier if you pick a .c file that doesn't exist; it doesn't matter, but it'll save you some navigation.)

Type, as the only thing in the buffer of the new file, four characters:

/**/

Again, do *not* press return at the end of the file.  Then, in succession:

^A
^K
^Y
[crash]

Comment 7 Jan Synacek 2018-10-04 08:34:32 UTC
I can't reproduce this. Both windowed and non-windowed emacs instances work fine.

Could you try with "emacs -Q" and "emacs -Q -nw" ?

Comment 8 Michael Bauer 2018-10-04 17:39:37 UTC
I installed a new instance of RHEL 7.5 workstation.  Immediately after the post-install reboot, I could reproduce the crash.  I got no change in behavior after running 'yum update', either before or after the reboot.  It crashed equally well in both window and terminal mode.  (Our Kickstart sequence does not include any invocation of 'yum update', as we use Puppet for post-install configuration.  For this test, I made a point of not invoking our Puppet setup, as I did not want to have any of our custom-built libraries crop up as potential interference.)

Though having just tested it on a newly-installed -- and fully Puppetized -- RHEL 7.5 server, I had to type '^Y' twice before it crashed.  Very odd.

Comment 9 Jan Synacek 2018-10-05 07:15:23 UTC
Right, I can now reproduce it. The c file has to be empty when emacs is started and the key sequence has to be exactly:
/ * * / ^A ^K ^Y ^Y

Thanks!

Comment 10 Jan Synacek 2018-11-19 15:18:39 UTC
The upstream version doesn't have this problem. Possibly, upstream commit 0248b0d70b891c952385daa787fb00c9bdd42935 fixes this, I need to take a look at it.

Comment 15 Chris Williams 2020-11-11 21:48:46 UTC
Red Hat Enterprise Linux 7 shipped it's final minor release on September 29th, 2020. 7.9 was the last minor releases scheduled for RHEL 7.
From intial triage it does not appear the remaining Bugzillas meet the inclusion criteria for Maintenance Phase 2 and will now be closed. 

From the RHEL life cycle page:
https://access.redhat.com/support/policy/updates/errata#Maintenance_Support_2_Phase
"During Maintenance Support 2 Phase for Red Hat Enterprise Linux version 7,Red Hat defined Critical and Important impact Security Advisories (RHSAs) and selected (at Red Hat discretion) Urgent Priority Bug Fix Advisories (RHBAs) may be released as they become available."

If this BZ was closed in error and meets the above criteria please re-open it flag for 7.9.z, provide suitable business and technical justifications, and follow the process for Accelerated Fixes:
https://source.redhat.com/groups/public/pnt-cxno/pnt_customer_experience_and_operations_wiki/support_delivery_accelerated_fix_release_handbook  

Feature Requests can re-opened and moved to RHEL 8 if the desired functionality is not already present in the product. 

Please reach out to the applicable Product Experience Engineer[0] if you have any questions or concerns.  

[0] https://bugzilla.redhat.com/page.cgi?id=agile_component_mapping.html&product=Red+Hat+Enterprise+Linux+7