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Message #85102
[Bug 1347147] Re: krb5 database operations enter infinite loop
This bug was fixed in the package gcc-4.8 - 4.8.4-2ubuntu1~14.04
---------------
gcc-4.8 (4.8.4-2ubuntu1~14.04) trusty-proposed; urgency=medium
* SRU LP: #1311866.
* Fix PR tree-optimization/63341 (wrong code, rs6000).
* Allow to turn off -Wformat using Wno-format. LP: #1401836.
* Fix PR target/60693 (x86, ice on valid code). LP: #1378737.
* Fix PR tree-optimization/61964 (wrong code). LP: #1347147.
* Fix GCC miscompilation with boost::asio::io_service::work. LP: #1338693.
* Fix PR target/61208 (POWER, wrong code). LP: #1322287.
* Fix ABI incompatibility between POWER and Z HTM builtins and intrinsics.
LP: #1320292.
* Fix PR c++/61046 (ice on invalid code). LP: #1313102.
* Fix wrong-code issue in the little endian vector API (ppc64el).
LP: #1311128.
* Fix PR tree-optimization/59358 (wrong code). LP: #1395019.
* Fix ice on ARM32. LP: #1268893.
* Don't apply the backport for PR61841 for trusty, causing link failures.
* Fix wrong code for vector doubleword extract (POWER). LP: #1437467.
gcc-4.8 (4.8.4-2ubuntu1) vivid; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.4-2) unstable; urgency=medium
* Update to SVN 20150426 (r222448) from the gcc-4_8-branch.
- Fix PR libstdc++/60966, PR c/61553, PR middle-end/63704,
PR target/61413 (ARM), PR target/64358 (RS6000), PR target/64479 (SH),
PR target/64409 (x86), PR rtl-optimization/64037, PR c++/64487,
PR c++/64251, PR c++/64297, PR fortran/63733, PR fortran/64244,
PR c/64766, PR target/64882, PR rtl-optimization/61058,
PR middle-end/43631, PR tree-optimization/64563, PR target/64513,
PR middle-end/57748, PR middle-end/57748, PR target/64795,
PR fortran/64528, PR fortran/56867, PR fortran/57023, PR c/57653,
PR tree-optimization/63844 (OpenMP), PR middle-end/64199 (ice on valid),
PR tree-optimization/64493 (ice on valid), PR tree-optimization/64495
(wrong code), PR tree-optimization/56273 (diagnostics),
PR tree-optimization/59124 (diagnostic), PR tree-optimization/64277
(diagnostic), PR lto/65015, PR target/65163 (SH), PR target/64113 (ALPHA,
link failure), PR rtl-optimization/64557, PR rtl-optimization/63475
(ALPHA, wrong code), PR rtl-optimization/63483 (ALPHA, wrong code),
PR target/64452 (AVR), PR target/64387 (x86, ice on valid),
PR target/64979 (wrong code), PR target/64580 (rs6000),
PR fortran/63744 (rejects valid), PR lto/65193 (ice on valid),
PR tree-optimization/61634 (ice on valid), PR target/65196 (AVR),
PR tree-optimization/63593 (ice on valid),
PR tree-optimization/65063 (wrong code), PR target/65286 (rs6000),
PR 65138/target (rs6000), PR target/53988 (SH), PR target/59593 (ARM),
PR target/64453 (ARM), PR middle-end/65409 (ice on valid),
PR tree-optimization/65388, PR fortran/65024 (ice),
PR fortran/60898 (ice on valid), PR fortran/61138, PR libgfortran/60956,
PR libstdc++/65279, PR libstdc++/65543, PR target/65849, PR target/65456,
PR target/65787, PR c++/65727, PR c++/65721, PR fortran/56674,
PR fortran/58813, PR fortran/59016, PR fortran/59024,
PR libgfortran/59513.
- s390 hotpatch backport.
- ppc64: Backport little endian swap optimization.
* Allow to build using gettext built with a newer GCC.
* Backport PR c++/62255 (rejects-valid).
* Update the Linaro support to the 4.8-2015.02 release.
* Configure with --enable-targets=powerpcle-linux on ppc64el for
backports to jessie, trusty, utopic and vivid.
* [AArch64] Fix output template for Scalar Neon->Neon register move.
LP: #1435342.
* Limit the omp.h multilib fix to Linux. Addresses: #778440.
* For ICEs, dump the preprocessed source file to stderr when in a
distro build environment.
* Apply the ada-mips patch for mips and mipsel targets only.
gcc-4.8 (4.8.4-1ubuntu15) vivid; urgency=medium
* Update to SVN 20150327 (r221736) from the gcc-4_8-branch.
- Fix PR libstdc++/65279, PR libstdc++/65543.
- ppc64: Backport little endian swap optimization.
* Limit the omp.h multilib fix to Linux. Addresses: #778440.
* For ICEs, dump the preprocessed source file to stderr when in a
distro build environment.
* Apply the ada-mips patch for mips and mipsel targets only.
gcc-4.8 (4.8.4-1ubuntu14) vivid; urgency=medium
* [AArch64] Fix output template for Scalar Neon->Neon register move.
LP: #1435342.
gcc-4.8 (4.8.4-1ubuntu11) vivid; urgency=medium
* Update to SVN 20150323 (r221594) from the gcc-4_8-branch.
- Fix PR fortran/61138, PR libgfortran/60956.
* Configure with --enable-targets=powerpcle-linux on ppc64el for vivid.
gcc-4.8 (4.8.4-1ubuntu10) vivid; urgency=medium
* Update to SVN 20150319 (r221517) from the gcc-4_8-branch.
- Fix PR middle-end/65409 (ice on valid), PR tree-optimization/65388,
PR fortran/65024 (ice), PR fortran/60898 (ice on valid).
* Configure with --enable-targets=powerpcle-linux on ppc64el for
backports to jessie, trusty and utopic.
gcc-4.8 (4.8.4-1ubuntu8) vivid; urgency=medium
* Fix ppc64el build.
gcc-4.8 (4.8.4-1ubuntu7) vivid; urgency=medium
* Update to SVN 20150309 (r221336) from the gcc-4_8-branch.
- Fix PR target/65286 (rs6000), PR 65138/target (rs6000),
PR target/53988 (SH), PR target/59593 (ARM), PR target/64453 (ARM).
* Update the Linaro support to the 4.8-2015.02 release.
gcc-4.8 (4.8.4-1ubuntu5) vivid; urgency=medium
* Update to SVN 20150228 (r221076) from the gcc-4_8-branch.
- Fix PR lto/65193 (ice on valid), PR tree-optimization/61634 (ice on
valid), PR target/65196 (AVR), PR tree-optimization/63593 (ice on valid),
PR tree-optimization/65063 (wrong code).
* Backport PR c++/62255 (rejects-valid).
gcc-4.8 (4.8.4-1ubuntu4) vivid; urgency=medium
* Update to SVN 20150225 (r220958) from the gcc-4_8-branch.
- Fix PR c/57653, PR tree-optimization/63844 (OpenMP), PR middle-end/64199
(ice on valid), PR tree-optimization/64493 (ice on valid),
PR tree-optimization/64495 (wrong code), PR tree-optimization/56273
(diagnostics), PR tree-optimization/59124 (diagnostic),
PR tree-optimization/64277 (diagnostic), PR lto/65015,
PR target/65163 (SH), PR target/64113 (ALPHA, link failure),
PR rtl-optimization/64557, PR rtl-optimization/63475 (ALPHA, wrong code),
PR rtl-optimization/63483 (ALPHA, wrong code), PR target/64452 (AVR),
PR target/64387 (x86, ice on valid), PR target/64979 (wrong code),
PR target/64580 (rs6000), PR fortran/63744 (rejects valid).
- s390 hotpatch backport.
gcc-4.8 (4.8.4-1ubuntu3) vivid; urgency=medium
* Update to SVN 20150205 (r220446) from the gcc-4_8-branch.
- Fix PR c/64766, PR target/64882, PR rtl-optimization/61058,
PR middle-end/43631, PR tree-optimization/64563, PR target/64513,
PR middle-end/57748, PR middle-end/57748, PR target/64795,
PR fortran/64528, PR fortran/56867, PR fortran/57023.
* Allow to build using gettext built with a newer GCC.
* Configure with --enable-targets=powerpcle-linux on ppc64el for
backports to jessie, trusty and utopic.
gcc-4.8 (4.8.4-1ubuntu2) vivid; urgency=medium
* Update to SVN 20150121 (r219965) from the gcc-4_8-branch.
- Fix PR libstdc++/60966, PR c/61553, PR middle-end/63704,
PR target/61413 (ARM), PR target/64358 (RS6000), PR target/64479 (SH),
PR target/64409 (x86), PR rtl-optimization/64037, PR c++/64487,
PR c++/64251, PR c++/64297, PR fortran/63733, PR fortran/64244.
gcc-4.8 (4.8.4-1ubuntu1) vivid; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.4-1) unstable; urgency=medium
* GCC 4.8.4 release.
- Fix PR target/61407 (darwin), PR middle-end/58624 (ice),
PR sanitizer/64265 (wrong code).
* Require recent binutils to pass go test failures.
gcc-4.8 (4.8.3-18ubuntu2) vivid; urgency=medium
* Update to SVN 20141211 (r218621) from the gcc-4_8-branch.
- Fix PR middle-end/64225 (missed optimization).
* Disable building the sanitizer libs on powerpc, ppc64 and ppc64. Not
yet completely ported, and causing kernel crashes running the tests.
* Don't build libphobos multilibs, there is no gdc-multilib built.
gcc-4.8 (4.8.3-18ubuntu1) vivid; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-18) unstable; urgency=medium
* Update to SVN 20141210 (r218575) from the gcc-4_8-branch.
- Fix PR target/55351 (SH), PR tree-optimization/61686,
PR bootstrap/64213.
* Fix cross builds with dpkg-architecture unconditionally exporting
target variables. For now specify the target architecture
in debian/target. This still needs to work with older dpkg versions,
so don't "simplify" the packaging. Addresses: #768167.
gcc-4.8 (4.8.3-17ubuntu1) vivid; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-17) unstable; urgency=medium
* Update to SVN 20141208 (r218508) from the gcc-4_8-branch.
- Fix PR target/59593 (ARM), PR c++/56493 (performance),
PR libstdc++/63840, PR libstdc++/61947, PR libstdc++/59603,
PR target/50751 (SH), PR rtl-optimization/64037i (wrong code).
gcc-4.8 (4.8.3-16) unstable; urgency=medium
* Update to SVN 20141202 (r218278) from the gcc-4_8-branch.
- Fix PR target/64115 (powerpc), PR middle-end/64111 (ice).
* Move libphobos2.a into the gcc_lib_dir. Closes: #771647.
gcc-4.8 (4.8.3-15) unstable; urgency=medium
* Update to SVN 20141128 (r218178) from the gcc-4_8-branch.
- Fix PR fortran/63938 (OpenMP), PR libgomp/61200 (OpenMP, ice),
PR middle-end/64067 (ice), PR rtl-optimization/63659 (wrong code),
PR preprocessor/60436 (ice).
- This adds the backports as found in gcc-4.9 4.9.2-4.
gcc-4.8 (4.8.3-14) unstable; urgency=medium
* Update to SVN 20141128 (r218162) from the gcc-4_8-branch.
- Fix PR target/56846 (ARM), PR tree-optimization/61969 (wrong code),
PR tree-optimization/62031 (wrong code), PR tree-optimization/63379
(wrong code), PR tree-optimization/63605 (wrong code), PR middle-end/63665
(wrong code), PR target/60111 (SH), PR target/63673 (rs6000),
PR target/63947 (x86), PR tree-optimization/62167 (wrong code),
PR tree-optimization/63841 (wrong code), PR ipa/63838 (wrong code),
PR c++/63455 (ice), PR c++/63415 (ice), PR c++/56710 (ice),
PR c++/58624 (ice), PR ada/47500, PR libfortran/63589.
- Fixes for Cortex-A53 Erratum 835769 (AArch64).
[ Matthias Klose ]
* Fix the libphobos cross build.
* Fix typo in the libstdc++ HTML docs. Addresses: #766498.
* Use doxygen's copy of jquery.js for the libstdc++ docs. Addresses: #766499.
* Support building the gcc-4.8 base package only.
[ Aurelien Jarno ]
* Always configure sh4-linux with --with-multilib-list=m4,m4-nofpu,
even with multilib disabled, as it doesn't produce additional
libraries.
gcc-4.8 (4.8.3-13) unstable; urgency=medium
* Update to SVN 20141014 (r216202) from the gcc-4_8-branch.
gcc-4.8 (4.8.3-12ubuntu3) utopic; urgency=medium
* Fix the libphobos cross build.
gcc-4.8 (4.8.3-12ubuntu2) utopic; urgency=medium
* Update to SVN 20141014 (r216202) from the gcc-4_8-branch.
- Fix PR libstdc++/63449 (docs), PR target/52941 (SH),
PR tree-optimization/63375 (wrong code), PR debug/63342 (ice),
PR target/63428 (wrong code), PR ada/63225 (ice),
PR fortran/59488 (OpenMP).
- x86: Enable reminder{sd,df,xf} and fmod{sf,df,xf} only
for flag_finite_math_only.
- rs6000 updates:
- Generate LE code for vec_lvsl and vec_lvsr that is compatible
with BE code.
- Warn for deprecated use of vec_lvsl and vec_lvsr for little endian.
- libcpp: Revise search_line_fast to avoid old unaligned load sequences.
gcc-4.8 (4.8.3-12ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-12) unstable; urgency=high
* Update to SVN 20140930 (r215742) from the gcc-4_8-branch.
[ Aurelien Jarno ]
* Default to mips64 ISA on mips64el, with tuning for mips64r2.
[ Matthias Klose ]
* Don't suggest libbacktrace-dbg and binutils-gold. Closes: #762640.
gcc-4.8 (4.8.3-11ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-11) unstable; urgency=medium
* Update to SVN 20140913 (r215236) from the gcc-4_8-branch.
* Fix installation of the libstdc++ documentation. Addresses: #760872.
gcc-4.8 (4.8.3-10ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-10) unstable; urgency=medium
* Update to SVN 20140831 (r214767) from the gcc-4_8-branch.
[ Samuel Thibault ]
* boehm-gc: use anonymous mmap instead of brk also on hurd-*.
gcc-4.8 (4.8.3-9ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-9) unstable; urgency=medium
* Update to SVN 20140820 (r214213) from the gcc-4_8-branch.
* Backport PR lto/62032.
* Fix PR tree-optimization/59586, graphite segfault, taken from the trunk.
LP: #1227789.
gcc-4.8 (4.8.3-8ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-8) unstable; urgency=medium
* Update to SVN 20140814 (r213981) from the gcc-4_8-branch.
* Add build dependency on systemtap-sdt-dev.
* Backport Python3 pretty printer support (Samuel Bronson).
* Proposed backport for PR libstdc++/61841. Closes: #749290.
* Build-depend on dpkg-dev (>= 1.7.11).
gcc-4.8 (4.8.3-7ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-7) unstable; urgency=medium
* Update to SVN 20140801 (r213447) from the gcc-4_8-branch.
- CVE-2014-5044, fix integer overflows in array allocation in libgfortran.
Closes: #756325.
- Fix PR tree-optimization/61964. LP: #1347147.
* Fix java.security symlink. Addresses: #756484.
gcc-4.8 (4.8.3-6ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
* Update to SVN 20140728 (r213129) from the gcc-4_8-branch.
- Properly fix PR libobjc/61920 on the 4.8 branch.
gcc-4.8 (4.8.3-6) unstable; urgency=medium
* Update to SVN 20140725 (r213051) from the gcc-4_8-branch.
* Don't gzip the xz compressed testsuite logs and summaries.
gcc-4.8 (4.8.3-5ubuntu2) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-5) unstable; urgency=medium
* Update to SVN 20140717 (r212756) from the gcc-4_8-branch.
* Warn about ppc ELFv2 ABI issues, which will change in GCC 4.10.
* Fix installing test logs and summaries.
gcc-4.8 (4.8.3-4ubuntu2) utopic; urgency=medium
* Update to SVN 20140701 (r212193) from the gcc-4_8-branch.
gcc-4.8 (4.8.3-4ubuntu1) utopic; urgency=medium
* Update to SVN 20140626 (r212051) from the gcc-4_8-branch.
gcc-4.8 (4.8.3-4) unstable; urgency=medium
* Update to SVN 20140626 (r212014) from the gcc-4_8-branch.
[ Aurelien Jarno ]
* Fix PR c++/61336, taken from the trunk.
[ Matthias Klose ]
* Fix removal of python byte-code files in libstdc++6. Addresses: #751435.
* Fix a segfault in the driver from calling free on non-malloc'd area.
* Remove version requirement for dependency on make. Addresses: #751891.
* Drop versioned build dependency on gdb, and apply the pretty printer
patch for libstdc++ based on the release.
gcc-4.8 (4.8.3-3ubuntu3) utopic; urgency=medium
* No-change rebuild.
gcc-4.8 (4.8.3-3ubuntu2) utopic; urgency=medium
* Update to SVN 20140616 (r211693) from the gcc-4_8-branch.
gcc-4.8 (4.8.3-3ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-3) unstable; urgency=medium
* Update to SVN 20140606 (r211339) from the gcc-4_8-branch.
* Don't install the libstdc++ pretty printer file into the debug directory,
but into the gdb auto-load directory.
* Fix the removal of the libstdc++6 package, removing byte-compiled pretty
printer files and pycache directories.
* Fix PR c++/61046, taken from the trunk. LP: #1313102.
gcc-4.8 (4.8.3-2ubuntu1) utopic; urgency=medium
* Update the fix for PR target/61208 for the Linaro branch.
gcc-4.8 (4.8.3-2) unstable; urgency=medium
* Update to SVN 20140527 (r210956) from the gcc-4_8-branch.
- Fix PR target/61208. Closes: #748422.
gcc-4.8 (4.8.3-1ubuntu4) utopic; urgency=medium
* Update to SVN 20140526 (r210209) from the gcc-4_8-branch.
- Fix PR target/61208 (ARM). Closes: #748422.
- PR target/61231 (powerpc).
- Fix HTM __builtin_ttest rtl expansion. LP: #1322287.
gcc-4.8 (4.8.3-1ubuntu3) utopic; urgency=medium
* Update the gcc-linaro-doc patch for GCC 4.8.3.
gcc-4.8 (4.8.3-1ubuntu2) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.3-1) unstable; urgency=medium
* GCC 4.8.3 release.
* Update the gdc tarball, drop the gdc-updates patch.
* Refresh patches.
* Build libitm on AArch64, patch taken from the trunk.
* Drop the libstdc++-arm-wno-abi patch, not needed anymore in 4.8.
gcc-4.8 (4.8.2-23ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.2-23) unstable; urgency=medium
* GCC 4.8.3 release candidate 1.
* Update to SVN 20140516 (r210514) from the gcc-4_8-branch.
* Apply the proposed patch for PR driver/61126.
* Update the libstdc++v-python3 patch. Closes: #748317.
* Update the gcc-default-format-security patch (Steve Beattie). LP: #1317305.
gcc-4.8 (4.8.2-22) unstable; urgency=medium
* Update to SVN 20140508 (r210209) from the gcc-4_8-branch.
* Install only versioned gcc-ar gcc-nm gcc-ranlib binaries for the hppa64
cross compiler, update hppa64 alternatives. Closes: #745967.
* Fix the as and ld symlinks for the hppa64 cross compiler.
* Ensure that the common libs (built from the next GCC version) are
available when building without common libs.
* Fix java.security symlink in libgcj14. Closes: #746786.
* Move the libstdc++ gdb pretty printers into libstdc++6, install the
-gdb.py files into /usr/share/gdb/auto-load.
* Set the 'Multi-Arch: same' attribute for packages, cross built with
with_deps_on_target_arch_pkgs=yes (Helmit Grohne). Closes: #716795.
* Build the gcc-X.Y-base package with with_deps_on_target_arch_pkgs=yes
(Helmit Grohne). Closes: #744782.
* Apply the proposed patch for PR driver/61106. Closes: #747345.
gcc-4.8 (4.8.2-21ubuntu1) utopic; urgency=medium
* Merge with Debian; remaining changes:
- Build from the upstream source.
gcc-4.8 (4.8.2-21) unstable; urgency=medium
* Update to SVN 20140424 (r209749) from the gcc-4_8-branch.
* gcc-4.8: Re-add lost dependency on libgcc-4.8-dev. Closes: #745709.
gcc-4.8 (4.8.2-20) unstable; urgency=medium
* Update to SVN 20140423 (r209678) from the gcc-4_8-branch.
* Explicitly configure with --disable-multilib on sparc64 when no
multilibs are requested (Helmut Grohne). Closes: #743342.
* Update powerpcspe patches for the branch (Helmut Grohne). Closes: #743718.
* Remove more mudflap left overs. Addresses: #742606.
* Adjust common_libs, libraries common to GCC 4.9.
* Disable running the testsuite on kfreebsd, hangs the buildds.
* Stop build packages built by GCC 4.9.
-- Matthias Klose <doko@xxxxxxxxxx> Fri, 27 Mar 2015 21:14:21 +0100
** Changed in: gcc-4.8 (Ubuntu Trusty)
Status: Fix Committed => Fix Released
--
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https://bugs.launchpad.net/bugs/1347147
Title:
krb5 database operations enter infinite loop
Status in The GNU Compiler Collection:
Fix Released
Status in Network Authentication System:
Unknown
Status in gcc-4.8 package in Ubuntu:
Fix Released
Status in gcc-4.9 package in Ubuntu:
Fix Released
Status in krb5 package in Ubuntu:
Fix Released
Status in gcc-4.8 source package in Trusty:
Fix Released
Status in krb5 source package in Trusty:
Fix Released
Bug description:
[Impact]
On krb5 KDC databases with more than a few hundred principals,
operations can enter an infinite loop in the database library. This
affects both read and write operations. If operators are fortunate,
they will encounter this bug while testing a migration. If they are
not so fortunate, they will encounter this bug in a production KDC
when the number of principals crosses the threshold where this bug
manifests, resulting in a service outage and possible database
corruption. Probably the only way to restore service in that
situation is to install a patched KDC or to downgrade to an unaffected
version.
Both Trusty and Utopic amd64 have been verified to have this issue.
One concrete reported example is an invocation of kdb5_util load (as
part of a slave KDC propagation) spinning:
http://mailman.mit.edu/pipermail/kerberos/2014-July/020007.html
Additional failure modes are likely
A branch is linked including the upstream work around for this bug,
along with two other patches to bugs already nominated for trusty
applied to the krb5 in trusty.
For utopic, the simplest fix is to rebuild krb5 with the compiler
currently in utopic. An alternative is to request that the Debian
maintainers (both monitoring this bug for such a request) upload the
upstream work around to Debian and sync that. You could do an ubuntu-
specific upload but it seems undesirable to introduce a change between
Ubuntu and Debian when all the right parties are happy to avoid it.
The upstream patch works around a compiler optimizer bug in the
gcc-4.8 series, which incorrectly deduces that a strict aliasing
violation has occurred and miscompiles part of the bundled libdb2
library that the KDC database back end depends upon. The
miscompilation causes a data structure to contain an inappropriate
cycle, which leads to an infinite loop when the structure is
traversed.
[Test Case]
apt-get install krb5-kdc krb5-admin-server
kdb5_util -W -r T create -s
awk 'BEGIN{ for (i = 0; i < 1024; i++) { printf("ank -randkey a%06d\n", i) } }' /dev/null | kadmin.local -r T
(Enter any password for the master key when requested.)
On platforms with this issue, kadmin.local spins consuming 100% CPU
after a few hundred principals have been created. (This is "a000762"
on two examples.)
To clean up,
rm /etc/krb5kdc/principal*
or
krb5kdc -r T destroy
but the latter can possibly enter the same infinite loop.
[Regression Potential]
Negligible.
It is theoretically possible that our upstream workaround, which
involves using TAILQ macros instead of CIRCLEQ macros in the bundled
libdb2 that backs the KDC database, will have some as-yet undiscovered
bugs or compiler interactions with consequences worse than this
current issue. I think this is rather unlikely.
The patched libdb2 passes both the extensive libdb2 test suite and the
rest of the krb5 test suite. Prior to patching, compiling krb5 with
an affected gcc would cause the krb5 test suite to stall when it
reached the libdb2 test suite. (The test suite stall is how we became
aware of the gcc optimizer bug.)
The BSD TAILQ macros are generally considered to be safer than the
CIRCLEQ macros, and the various open-source BSD derivatives have made
the corresponding change to their libdb sources years ago, with no
reported ill effects that I can see.
Original report from Ben Kaduk:
==========
In some conditions, propagating a kerberos database to a slave KDC server can stall.
This is due to a misoptimization by gcc 4.8 of the CIRCLEQ famliy of macros, apparently due to overzealous strict aliasing deductions.
One case of this stall is reported at
http://mailman.mit.edu/pipermail/kerberos/2014-July/020007.html (and
the rest of the thread), and there is an entry in the upstream
bugtracker at http://krbdev.mit.edu/rt/Ticket/Display.html?id=7860 .
gcc 4.9 (as used in Debian unstable at present) is not believed to
induce this problem. Upstream has patched their code to use the TAILQ
family of macros instead, as a workaround, but that workaround has not
yet appeared in an upstream release:
https://github.com/krb5/krb5/commit/26d8744129
Because of the different compiler versions used on Debian and Ubuntu,
I am filing this as an Ubuntu-specific bug.
To manage notifications about this bug go to:
https://bugs.launchpad.net/gcc/+bug/1347147/+subscriptions
References
