RHBA-2009:0464 - Bug Fix Advisory

Topic

An updated libunwind package that removes the possibility of a crash when
using unwinding capabilities is now available.

Description

The libunwind package provides a portable C-based API for determining the
call-chain of a program. In addition, libunwind makes it possible to
manipulate the saved state of a call-frame, and resume execution at any
call-chain point.

This updated libunwind package fixes the following bug:

• C++ programs which used standard C++ exceptions and were linked with the

libunwind library could crash, due to a conflict between the unwinding
capabilities contained in GCC and those provided by libunwind. libunwind
used an outdated Application Binary Interface (ABI) which did not provide
the GetIPInfo() function. When the libunwind unwinder was preferred over
the GCC unwinder, then the missing GetIPInfo() function (which was provided
by the GCC unwinder) was used together with libunwind's unwinding support.
Because GCC's GetIPInfo() function must access the (valid) state of the GCC
unwinder, an application crash could result. Because of this ABI change,
libunwind required a small extension to its ABI to update it to the current
unwinding ABI. This updated package provides that extension, thus removing
the possibility for unwinding conflict and potential application crash.
(BZ#480412)

Note: it is only necessary to update a system with these libunwind packages
in order to avoid the potential application crash detailed above. It is not
necessary to update any gcc packages.

All users who require unwinding capabilities are advised to upgrade to this
updated package, which resolves this issue.

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 ia64

Fixes

• BZ - 480412 - c++ exception bug when linked with libunwind on ia64

CVEs

(none)

References

(none)