Bug 102520
| Summary: | execshield proc variable needs to be removed | ||||||
|---|---|---|---|---|---|---|---|
| Product: | Red Hat Enterprise Linux 3 | Reporter: | John Reiser <jreiser> | ||||
| Component: | kernel | Assignee: | Arjan van de Ven <arjanv> | ||||
| Status: | CLOSED RAWHIDE | QA Contact: | Brian Brock <bbrock> | ||||
| Severity: | medium | Docs Contact: | |||||
| Priority: | medium | ||||||
| Version: | 3.0 | ||||||
| Target Milestone: | --- | ||||||
| Target Release: | --- | ||||||
| Hardware: | athlon | ||||||
| OS: | Linux | ||||||
| Whiteboard: | |||||||
| Fixed In Version: | Doc Type: | Bug Fix | |||||
| Doc Text: | Story Points: | --- | |||||
| Clone Of: | Environment: | ||||||
| Last Closed: | 2003-08-22 00:37:54 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: | |||||||
| Bug Depends On: | |||||||
| Bug Blocks: | 101028 | ||||||
| Attachments: |
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Created attachment 93682 [details]
failed results of trying to change exec-shield parameter
the /proc/sys/kernel/exec-shield value has absolutely no effect and will indeed be removed. Is there [will there be] any way to get the old behavior of sequential allocation beginning at TASK_UNMAPPED_BASE [or replacement]? there is no more TASK_UNMAPPED_BASE actually; allocations are now done top down instead. Fix confirmed with 2.4.21-1.1931.2.399.entsmp. |
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030709 Description of problem: A program which analyzes another running program wants to see the previous behavior of mmap(0, ...) beginning its search for a free page frame at TASK_UNMAPPED_BASE (0x40000000 typical). Exec-shield randomizes the value to be something larger than 0x00100000 instead. This behavior is supposed to be controlled by /proc/sys/kernel/exec-shield, but trying all four legal values [0, 1, 2, 3] has no observable effect: the address used for mmap(0, ...) is always random > 0x00100000. Version-Release number of selected component (if applicable): kernel-2.4.21-1.1931.2.393.ent How reproducible: Always Steps to Reproduce: 1. Run script (as root) ----- #!/bin/bash for j in 0 1 2 3 do echo; echo ===== $j echo $j >/proc/sys/kernel/exec-shield echo exec-shield = $(cat /proc/sys/kernel/exec-shield) cat /proc/self/maps done ----- 2. 3. Actual Results: Shared libraries are seen at "random" addresses > 0x00100000; output attached. Expected Results: One of those values for exec-shield should force the old behavior of allocating page frames sequentially beginning at TASK_UNMAPPED_BASE (typically 0x40000000 in 2.4.20, for example). Additional info: # uname -a Linux taroon 2.4.21-1.1931.2.393.ent #1 Wed Aug 13 21:38:34 EDT 2003 i686 athlon i386 GNU/Linux