RHBA-2009:1283 - Bug Fix Advisory

Topic

Updated crash packages that resolve several issues are now available.

Description

The crash packages are used to investigate live systems and kernel core
dumps created from the netdump, diskdump and kdump facilities.

These updated crash packages are rebased to upstream version 4.0-8.9
(BZ#494028) and provide fixes for the following bugs:

• if entered alone on the command line, the "set" command would cause a

segmentation violation, because there is no concept of a "context" in the
Xen hypervisor. Crash now prompts the user to provide an option with "set",
and provides more meaningful error messages if the option selected is not
applicable. (BZ#462819)

• crash would indicate "irq: invalid structure size: gate_struct" and dump

a stack trace leading to x86_64_display_idt_table() when the "irq -d"
option was run on AMD64 and Intel 64 Xen kernels. Now it will indicate
that the -d option is not applicable. (BZ#464116)

• the "bt" command did not work correctly when running against the Xen

hypervisor binary. The "bt -o" option, and setting it to run by default
with "bt -O", would fail with the vmlinux-specific error message "bt:
invalid structure size: desc_struct" with a stack trace leading to
read_idt_table(). Now, it will display the generic error message "bt: -o
option not supported or applicable on this architecture or kernel". The
"bt -e" or "bt -E" will also display the same error message, as opposed to
the command usage message. Lastly, the "bt -R" option would cause a
segmentation violation; it has been fixed to work as it was designed.
(BZ#464288)

• when run on a Xen hypervisor in which the backtrace leads to either

"process_softirqs" or "page_fault", the "bt" command backtrace would
indicate: "bt: cannot resolve stack trace". The recovery code would then
terminate the command with the nonsensical error message: "bt: invalid
structure size: task_struct". The command now properly terminates the
backtrace. (BZ#474712, BZ#466724)

• when run against the Xen hypervisor where the number of physical cpus

outnumber the MAX_VIRT_CPUS value for the processor type, the "bt -a"
command would fail after displaying backtraces for the first 32
(MAX_VIRT_CPUS) pcpus with the the error message: "bt: invalid vcpu". The
command now shows backtraces for all pcpus. (BZ#471790)

• the "mod -[sS]" command would fail with the error message: "mod: cannot

find or load object file for <name> module" if the target module object
filename contains both underscore and dash characters. Crash now parses
these filenames correctly. (BZ#480136)

• an existing Itanium INIT and MCA handler bug incorrectly writes the pseudo

task's command name in its comm[] name string such that the CPU number may
not be part of the string. The "bt" command could not link back to a PID 0
swapper task that was interrupted by an Itanium INIT or MCA exception, and
displayed the error message: "bt: unwind: failed to locate return link
(ip=0x0)!" Crash now uses a different method to obtain the CPU number for
the interrupted task, and the backtrace correctly transitions back to the
interrupted task. (BZ#487429)

• the starting backtrace location of active, non-crashing, xen dom0 tasks

are not available in kdump dumpfiles, nor is there anything that can be
searched for in their respective stacks. Therefore, for these tasks, the
"bt" command would show either an empty backtrace or an invalid backtrace
starting at the last location where schedule() had been called. Instead,
the "bt" command now provides an error message for these tasks that
indicated "bt: starting backtrace locations of the active (non-crashing)
xen tasks cannot be determined: try -t or -T options". (BZ#495586)

• Running the "bt" command against an x86 Xen kernel vmcore, the transition

from the IRQ stack back to the process stack led to a segmentation fault.
(BZ#478904)

The upstream changelog referenced below details additional bug fixes and
enhancements provided by the rebase of this package.

All users of crash are advised to upgrade to these updated packages, which
resolve these issues.

Solution

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

This update is available via Red Hat Network. Details on how to use
the Red Hat Network to apply this update are available at
http://kbase.redhat.com/faq/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 - 466724 - [5.3][xen] bt: invalid structure size: task_struct
• BZ - 480136 - mod: cannot find or load object file for dm_region_hash module
• BZ - 487429 - Use bt->tc->processor instead of bt->tc->comm to retrieve processor numbers
• BZ - 494028 - Rebase request for crash utility RHEL5.4 errata

CVEs

(none)

References

• http://people.redhat.com/anderson/crash.changelog.html