Bug 78413 – (alpha) deflate.c mis-compiled with -O2

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Bug 78413 - (alpha) deflate.c mis-compiled with -O2

Summary:	(alpha) deflate.c mis-compiled with -O2

Status:	CLOSED NOTABUG

Aliases:	None

Product:	Red Hat Raw Hide
Classification:	Retired
Component:	gcc3 (Show other bugs)
Sub Component:
Version:	1.0
Hardware:	alpha Linux

Priority	medium Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	Richard Henderson
QA Contact:	Ben Levenson
Docs Contact:

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2002-11-22 11:13 EST by Jeff Johnson
Modified:	2007-04-18 12:48 EDT (History)
CC List:	0 users

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:
Story Points:	---
Clone Of:
Environment:
Last Closed:	2003-01-31 00:21:40 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
file to reproduce problem (63.95 KB, text/plain) 2002-11-22 11:15 EST, Jeff Johnson	no flags	Details
Add an attachment (proposed patch, testcase, etc.)

Groups: None (edit)

Description Jeff Johnson 2002-11-22 11:13:33 EST

Description of Problem:


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


How Reproducible:


Steps to Reproduce:
1. gzip lutBS08.pcf segfaults
2. compile deflate.c with -O0 rather than -O2
3. gzip lutBS08.pcf compresses

Actual Results:


Expected Results:


Additional Information:

Comment 1 Jeff Johnson 2002-11-22 11:15:17 EST

Created attachment 86066 [details]
file to reproduce problem

Comment 2 Jeff Johnson 2002-11-22 11:16:45 EST

Workaround (compile deflate.c with -O0) in gzip-1.3.3-7

Comment 3 Jeff Johnson 2002-12-02 10:01:06 EST

This smells like a compiler bug, since -O0 is a fix.

Bounce back to gzip so I can get the workaround removed, please.

Comment 4 Richard Henderson 2003-01-31 00:21:40 EST

Using no optimization does *not* fix the problem for me.
I see the same crash with all files compiled -O0.  Sticking
the debugger on this shows that the program is walking off
the end of the data segment.

I rebuilt gzip with gcc 2.96, which does not exhibit the
crash and debugged things there, trying to see what happens
differently.  Turns out: nothing at all.  The code really 
does walk off the end of the "window" array.

With the 2.96 compiler, the data segment is aligned differently,
and the end of the last page ends 0x1990 bytes past the end of
the window array.  With the 3.2 compiler, the last page ends 
0xd0 bytes past the end of the array.

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