Bug 58006
| Summary: | "limit datasize" does not work | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Product: | [Retired] Red Hat Linux | Reporter: | Jamie Zawinski <jwz> | ||||||
| Component: | glibc | Assignee: | Jakub Jelinek <jakub> | ||||||
| Status: | CLOSED NOTABUG | QA Contact: | Brian Brock <bbrock> | ||||||
| Severity: | medium | Docs Contact: | |||||||
| Priority: | medium | ||||||||
| Version: | 7.2 | CC: | fweimer | ||||||
| Target Milestone: | --- | ||||||||
| Target Release: | --- | ||||||||
| Hardware: | i386 | ||||||||
| OS: | Linux | ||||||||
| Whiteboard: | |||||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||||
| Doc Text: | Story Points: | --- | |||||||
| Clone Of: | Environment: | ||||||||
| Last Closed: | 2004-08-26 04:19:17 UTC | Type: | --- | ||||||
| Regression: | --- | Mount Type: | --- | ||||||
| Documentation: | --- | CRM: | |||||||
| Verified Versions: | Category: | --- | |||||||
| oVirt Team: | --- | RHEL 7.3 requirements from Atomic Host: | |||||||
| Cloudforms Team: | --- | Target Upstream Version: | |||||||
| Embargoed: | |||||||||
| Attachments: |
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Created attachment 41831 [details]
malloc-bomb.c source: program that verbosely allocates memory
Created attachment 41832 [details]
limiter.pl -- program to demonstrate that setrlimit() works correctly
The difference is that limiter.pl (and (ulimit -v) referenced
in malloc-bomb.c) use RLIMIT_AS, but (limit datasize) uses
RLIMIT_DATA. If you use (limit vmemoryuse) under tcsh
(to also use RLIMIT_AS), bash and tcsh behave exactly the same.
OTOH SUSv3 specifies:
RLIMIT_DATA
This is the maximum size of a processâ data segment, in
bytes.
If this limit is exceeded, the malloc() function shall
fail with
errno set to [ENOMEM].
In fact, RLIMIT_DATA limits memory allocated through sbrk (),
but malloc () in glibc can also use mmap (). This seems like a
violation of the standard by glibc.
That POSIX text is ancient. If one insists to have this definition of RLIMIT_DATA, simply start the application with MALLOC_MMAP_THRESHOLD_=0 in the environment. That is perfectly fine with POSIX. POSIX specifies only that there must be one environment in which all the rules apply. The default environment does not have this stupid limitation which nobody wants. |
From Bugzilla Helper: User-Agent: Mozilla/4.78 [en] (X11; U; Linux 2.4.9-13smp i686; Nav) Description of problem: "limit datasize 10m" should limit the sbrk+stack size to 10M in tcsh; programs that try to brk beyond that should fail (causing brk/malloc to return 0.) This does not work in tcsh 6.10; tested on Red Hat 6.2, 7.0, and 7.2. Version-Release number of selected component (if applicable): How reproducible: Always Steps to Reproduce: 1. tcsh 2. limit datasize 5m 3. ./malloc-bomb Actual Results: Program continues allocating memory forever. Expected Results: Program should have died after allocating around 5M. Additional info: Attached is the source to the malloc-bomb program I used to test this. Following that is the source to limiter.pl, a perl script that *does* work ("./limiter.pl 5M malloc-bomb"). That limiter.pl works demonstrates that the problem is with tcsh and not with the setrlimit() syscall. FWIW, bash 1.14 also had this problem, but it appears to have been corrected by bash 2.04.