Bug 1518243 – GDB no longer dumps memory regions marked with the VM_DONTDUMP flag

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Bug 1518243 - GDB no longer dumps memory regions marked with the VM_DONTDUMP flag

Summary:	GDB no longer dumps memory regions marked with the VM_DONTDUMP flag

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise Linux 7
Classification:	Red Hat
Component:	gdb (Show other bugs)
Sub Component:
Version:	7.4
Hardware:	Unspecified Unspecified

Priority	high Severity high
Target Milestone:	rc
Target Release:	---
Assigned To:	Jan Kratochvil
QA Contact:	Michal Kolar
Docs Contact:	Vladimír Slávik

URL:
Whiteboard:
Keywords:	Regression, ZStream

Depends On:
Blocks:	1524312
	Show dependency tree / graph

Reported:	2017-11-28 08:34 EST by Sergio Lopez
Modified:	2018-04-10 06:26 EDT (History)
CC List:	12 users (show)

See Also:
Fixed In Version:	gdb-7.6.1-108.el7
Doc Type:	Bug Fix
Doc Text:	GDB can again dump memory protected by the "VM_DONTDUMP" flag Previous changes to the GNU Debugger GDB made the behavior of the "gcore" command more similar to the behavior of the Linux kernel when dumping process memory to increase data security. Consequently, users of GDB could not dump memory protected by the "VM_DONTDUMP" flag. The new "set dump-excluded-mappings" setting has been added to GDB to enable dumping of memory with this flag. As a result, users can dump the whole process memory with GDB again.
Story Points:	---
Clone Of:
Clones:	1524312 (view as bug list)
Environment:
Last Closed:	2018-04-10 06:25:07 EDT
Type:	Bug
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

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External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHBA-2018:0701	None	None	None	2018-04-10 06:26 EDT

Groups: None (edit)

Description Sergio Lopez 2017-11-28 08:34:12 EST

Versions prior to gdb-7.6.1-83.el7, unconditionally included all memory regions when generating a dump file. Starting with this version, by default GDB will both inspect /proc/PID/coredump_filter, and unconditionally ignore memory regions marked with VM_DONTDUMP.

While it's possible requesting to GDB to ignore /proc/PID/coredump_filter by using the 'set use-coredump-filter' command, there's no way to request it to ignore the VM_DONTDUMP flag.

The change that altered the behavior is this one:

commit 38e1562bc360e0b89490b9b6903e1982a2f2f7fe
Author: Jan Kratochvil <jan.kratochvil@redhat.com>
Date:   Fri Nov 27 20:43:41 2015 +0100

    Support for /proc/PID/coredump_filter (Sergio Durigan Junior, RH
BZ 1265351).

    Sergio Durigan Junior, RH BZ 1265351

    7.6.1-83.el7

    - Resolves: rhbz#1265351

I've posted a tentative fix for this upstream:

 - https://sourceware.org/ml/gdb-patches/2017-11/msg00724.html

Comment 10 Michal Kolar 2017-12-12 09:38:23 EST

Reproduced against gdb-7.6.1-100.el7 and verified against gdb-7.6.1-108.el7.

Comment 17 errata-xmlrpc 2018-04-10 06:25:07 EDT

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2018:0701

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