Bug 1300958
| Summary: | segfault in script after ulimit -v [RHEL-6] | ||||||||
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| Product: | Red Hat Enterprise Linux 6 | Reporter: | Martin Kyral <mkyral> | ||||||
| Component: | zsh | Assignee: | Kamil Dudka <kdudka> | ||||||
| Status: | CLOSED WONTFIX | QA Contact: | BaseOS QE - Apps <qe-baseos-apps> | ||||||
| Severity: | low | Docs Contact: | |||||||
| Priority: | unspecified | ||||||||
| Version: | 6.7 | CC: | jkejda, kdudka | ||||||
| Target Milestone: | rc | Keywords: | Patch | ||||||
| Target Release: | --- | ||||||||
| Hardware: | Unspecified | ||||||||
| OS: | Unspecified | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | Doc Type: | If docs needed, set a value | |||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | |||||||||
| : | 1302229 (view as bug list) | Environment: | |||||||
| Last Closed: | 2017-07-03 12:47:09 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: | 1302229 | ||||||||
| Bug Blocks: | |||||||||
| Attachments: |
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Thank you for reporting the bug. From the backtrace it is clear that it crashes due to infinite recursion and stack overflow. zalloc() fails to allocate memory, so it wants to print a fatal error message and exit. The problem is that zerr(), which is used to print the error message, transitively calls back to zalloc(). In order to prevent the stack overflow, we need to: 1. either make zalloc() not call zerr(), 2. make zerr() not transitively call back to zalloc(), or 3. introduce a flag that will break the recursion in cases like this. Created attachment 1118021 [details]
proof-of-concept reproducer
I have attached a universal reproducer script. It is not completely reliable because dynamic linker and pthread run-time may run out of memory sooner than zsh itself in some cases. Nevertheless, I am able to trigger the infinite recursion with upstream git HEAD if I create a statically linked executable.
reported upstream: http://www.zsh.org/mla/workers/2016/msg00310.html .. and there's already proposed fix. Thanks! upstream commits: https://sourceforge.net/p/zsh/code/ci/be32864e https://sourceforge.net/p/zsh/code/ci/69c86cd2 fixed in zsh-5.2-4.fc24 Red Hat Enterprise Linux 6 transitioned to the Production 3 Phase on May 10, 2017. During the Production 3 Phase, Critical impact Security Advisories (RHSAs) and selected Urgent Priority Bug Fix Advisories (RHBAs) may be released as they become available. The official life cycle policy can be reviewed here: http://redhat.com/rhel/lifecycle This issue does not appear to meet the inclusion criteria for the Production Phase 3 and will be marked as CLOSED/WONTFIX. If this remains a critical requirement, please contact Red Hat Customer Support to request a re-evaluation of the issue, citing a clear business justification. Red Hat Customer Support can be contacted via the Red Hat Customer Portal at the following URL: https://access.redhat.com |
Created attachment 1117132 [details] backtrace Description of problem: Script containing ulimit -v 100000 causes zsh to segfault: [0 root@qeos-21 test]# cat segv.sh ulimit -v 100000 ls [0 root@qeos-21 test]# zsh segv.sh Segmentation fault (core dumped) [0 root@qeos-21 test]# echo $? 139 By further examination I found out, that the problem is bad handling of the memory allocation if the memory limit set by ulimit -v is too strict. ksh and bash are ok with this particular value. When I set it really low (ulimit -v 100), the script gets killed by SIGKILL which is better than SIGSEGV. Version-Release number of selected component (if applicable): zsh-4.3.11-4.el6_7.1 How reproducible: always Steps to Reproduce: 1. see description 2. 3. Actual results: [0 root@qeos-21 test]# zsh segv.sh Segmentation fault (core dumped) [0 root@qeos-21 test]# echo $? 139 Expected results: [0 root@qeos-21 test]# zsh segv.sh Killed [0 root@qeos-21 test]# echo $? 137 Additional info: It may be necessary to use lower ulimit -v value to reproduce.