RHBA-2012:0203 - Bug Fix Advisory

Topic

An updated crash package that fixes various bugs is now available for Red Hat
Enterprise Linux 5

Description

The crash package provides a self-contained tool that can be used to investigate
live systems, and kernel core dumps created from the netdump, diskdump, kdump,
and Xen/KVM "virsh dump" facilities from Red Hat Enterprise Linux.

This updated crash package includes fixes for the following bugs:

• The crash package has been upgraded to upstream version 5.1.8, which provides

a number of enhancements and bug fixes over the previous version. (BZ#715072)

• On AMD64 and Intel 64 architectures, the "bt" command failed when the shutdown

NMI was issued to a 32-bit task that had executed a "sysenter" instruction and
the RSP still contained the zero value loaded from the MSR_IA32_SYSENTER_ESP
register. Consequently, the backtrace issued the following warning message:

"WARNING: possibly bogus exception frame"

and was unable to make a transition from the NMI exception stack back to the
process stack. With this update, the underlying source code has been modified to
address this issue, and the aforementioned command no longer fails. (BZ#676408)

• On AMD64 and Intel 64 architectures, the "bt" command failed with several

backtrace errors for non-crashing active tasks:

"bt: cannot resolve stack trace"

This was due to a failure to properly transition from the shutdown NMI stack
back to the process stack. This update fixes these errors, and executing the
"bt" command on non-crashing active tasks works as expected. (BZ#713050)

• KVM virtual systems contain an I/O hole in the physical memory region from

0xe0000000 to 0x100000000 (3.5 GB to 4 GB). If a guest is provisioned with more
than 3.5 GB of RAM, then the memory above 3.5 GB is "pushed up" to start at
0x100000000 (4 GB). However, the "ram" device headers in the KVM dumpfiles do
not reflect that. As a result, numerous error messages were displayed during
invocation, and the session would often fail. With this update, the crash
utility takes the I/O hole into account despite the fact that the "ram" device
headers in KVM dumpfiles do not; consequently, error messages are no longer
displayed during invocation. (BZ#716327)

• The KVM I/O hole size is currently set to either 1 GB or 512 MB, but its

setting is hardwired into the Qemu code that was used to create the dumpfile.
The dumpfile is a "savevm" file that is designed to be used for guest migration,
and since inter-version save/load operations are not supported, the I/O hole
information does not have to be encoded into the dumpfile. Prior to this update,
the I/O hole for dumpfiles created by older Qemu version was not being set to
1GB, so if the KVM guest was configured with more than 3GB of memory, the crash
session would typically display numerous "read error" messages during session
initialization. With this update, the crash session does not return any error
messages during session initialization. (BZ#715070)

All users of crash are advised to upgrade to this updated package, which
resolves these issues.

Solution

Before applying this update, make sure all previously-released errata
relevant to your system have been applied.

This update is available via the Red Hat Network. Details on how to
use the Red Hat Network to apply this update are available at
https://access.redhat.com/kb/docs/DOC-11259

Affected Products

• Red Hat Enterprise Linux Server 5 x86_64
• Red Hat Enterprise Linux Server 5 ia64
• Red Hat Enterprise Linux Server 5 i386
• Red Hat Enterprise Linux Workstation 5 x86_64
• Red Hat Enterprise Linux Workstation 5 i386
• Red Hat Enterprise Linux Desktop 5 x86_64
• Red Hat Enterprise Linux Desktop 5 i386
• Red Hat Enterprise Linux for IBM z Systems 5 s390x
• Red Hat Enterprise Linux for Power, big endian 5 ppc
• Red Hat Enterprise Linux Server from RHUI 5 x86_64
• Red Hat Enterprise Linux Server from RHUI 5 i386

Fixes

• BZ - 676408 - bt: WARNING: possibly bogus exception frame
• BZ - 715070 - crash: RHEL5 "virsh dump" support fails if guest has >= 3GB memory
• BZ - 715072 - Rebase request for crash utility RHEL5.8 errata

CVEs

(none)

References

(none)