Uninitialized variables and F37
by Steve Grubb
Hello,
This is a continuation of the discussion from F36 Change: GNU Toolchain
Update.
Uninitialized variables are a big problem. They can be sources of information
exposure if parts of a buffer are not initialized. They can also cause
unexpected execution paths if the attacker can groom the memory to a value of
their choosing. If the variable is a pointer to heap, this can cause free to
corrupt memory under certain circumstances. If the uninitialized memory is
part of user input, this can lead to improper input validation. This is not
hypothetical. All of these come from a paper doing an emprical study of
android flaws. [1] The data used in the paper is here. [2]
Part of the problem is that compilers and static analysis tools can't always
find them. I created a test program that has 8 uses of unintialized variables.
Gcc 11 misses all of them. Gcc 12 finds 2. Clang 13 finds 1. cppcheck finds 2 or
3 - but does so much complaining you'd think it found all. Valgrind finds 2.
Flexelint, a commercial linter, finds 1.
Since tools can't always find them, the only option we have right now is force
initialization to something the attacker cannot control. Kees Cook started a
discussion on the llvm developers mail list a while back. He makes a very
clear argument. I would be repeating his points, so please read the original
discussion here (also read the replies):
https://lists.llvm.org/pipermail/cfe-dev/2020-April/065221.html
He talks about -ftrivial-auto-var-init=zero being used for production builds
and -ftrivial-auto-var-init=<pattern> being used for debug builds. The use
is not just the kernel. Consider a server that returns data across the
network to a client. It could possibly leak crypto keys or passwords if the
returned data structure has uninitialized memory.
For more background, the creator of this technology for LLVM presented a talk
about this feature at a past LLVM developer conference:
https://www.youtube.com/watch?v=I-XUHPimq3o
He said this would have prevented over 900 fixed CVE's in Chrome and 12% of
all Android CVE's.
From deep inside the LLVM thread above, comes this nugget:
---
To add in, we (Microsoft) currently use zero initialization technology in
Visual Studio in a large amount of production code we ship to customers (all
kernel components, a number of user-mode components). This code is both C and
C++.
We already have had multiple vulnerabilities killed because we shipped this
technology in production. We received bug reports with repros that worked on
older versions of Windows without the mitigation and new versions of Windows
that do have it. The new versions don't repro, the old ones do.
---
Microsoft is also digging in to uninitialized variables. They have a lengthy
blog post that talks about extending this to heap memory. [3]
I think this would be an important step forward to turn this on across all
compilations. We could wipe out an entire class of bugs in one fell swoop.
But then, what about heap allocations? Calloc has existed for a long time. It
might be worthwhile to have a CFLAG that can tell glibc (or other allocators)
to substitute something like calloc for malloc.
Cheers,
-Steve
[1] - https://picture.iczhiku.com/resource/paper/shkeTWJEaFUuWCMc.pdf
[2] - http://ml-papers.gitlab.io/android.vulnerabilities-2017/appendix/
MSR2017/vulnerabilitiesList.html
[3] - https://msrc-blog.microsoft.com/2020/07/02/solving-uninitialized-kernel-p...
2 days, 12 hours
Heads-up: grpc 1.41.0 coming to Rawhide with C (core) and C++ soname
bumps
by Ben Beasley
In one week (October 6), or slightly later, I will build grpc 1.41.0 for
Rawhide (F36). Fedora 35 will remain on 1.39.1.
As is traditional for minor releases of grpc, the C++ ABI was broken
(soversion bumped from 1.40 to 1.41). This time, the C (core) ABI was
also broken (soversion bumped from 18 to 19).
I will coordinate builds in a side tag of packages that use the C (core)
and/or C++ libraries. Maintainers of the following packages should have
received this email directly:
• bear
• frr
• perl-grpc-xs
Packages that use the Python bindings should be unaffected, as there
should be no incompatible API changes:
• buildstream
• python-chirpstack-api
• python-etcd3
• python-google-api-core
• python-google-cloud-core
• python-grpc-google-iam
• python-opencensus (orphaned)
• python-opencensus-proto
• python-opentelemetry
• python-pytest-grpc
• python-xds-protos
1 week, 2 days
F37 Change: Enable read only /sysroot for Fedora Silverblue & Kinoite
(Self-Contained Change proposal)
by Ben Cotton
https://fedoraproject.org/wiki/Changes/Silverblue_Kinoite_readonly_sysroot
== Summary ==
This change is about enabling an opt-in ostree feature that re-mounts
`/sysroot` as read only to avoid accidental changes.
Users and administrators are not expected to directly interact with
the content available there and should instead use the interface
offered by rpm-ostree, GNOME Software or (soon) Plasma Discover to
manage their system.
== Owner ==
* Name: [[User:Siosm| Timothée Ravier]], [[User:Tpopela| Tomáš
Popela]], [[User:jkonecny| Jiří Konečný]]
* Email: siosm(a)fedoraproject.org, tpopela(a)fedoraproject.org, jkonecny(a)redhat.com
* FESCo shepherd: [[User:Ngompa| Neal Gompa]] ngompa(a)fedoraproject.org
== Detailed Description ==
On rpm-ostree based systems, the real root (the root directory of the
root partition on the disk) is mounted under the `/sysroot` path. By
default it contains the state of the system (the content of `var` and
`etc`) as well as the system versions themselves (each versioned copy
of `/usr`) in the ostree repository (`/ostree/repo`).
This change is about enabling an opt-in ostree feature that re-mounts
`/sysroot` as read only to avoid accidental changes.
Users and administrators are not expected to directly interact with
the content available there and should instead use the interface
offered by rpm-ostree, GNOME Software or (soon) Plasma Discover to
manage their system.
Example of issue: https://github.com/fedora-silverblue/issue-tracker/issues/232
This change replicates for Fedora Silverblue/Kinoite what has been
done in Fedora CoreOS in a previous release.
== Feedback ==
None so far.
== Benefit to Fedora ==
This will make Fedora Silverblue/Kinoite more robust to accidental
damage from users.
== Scope ==
* Proposal owners:
** Work on the changes requires for new installations (potentially
Anaconda configuration changes) and support for in place updates for
existing installations (requires a two step process).
* Other developers:
** Potential Anaconda changes required.
* Release engineering: N/A
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives: N/A
== Upgrade/compatibility impact ==
We will create a systemd unit that perform the updates in place for
existing systems. This will require a two step process (changing the
existing kernel arguments, and then enabling the ostree feature). Once
the feature is enabled, user won't be able to rollback to previous
deployments where the kernel argument is not set. We will have to
clearly document that in the documentation for easier troubleshooting.
== How To Test ==
Only try the following if you are confortable debugging an un-bootable
system and have made backups!
`$ sudo rpm-ostree kargs --append-if-missing=rw`
`$ sudo ostree config --repo=/sysroot/ostree/repo set "sysroot.readonly" "true"`
`$ sudo systemctl reboot`
Note that you can not "rollback" to the previous deployment to undo
this change. You will have to boot into a Live ISO and edit the config
file in the ostree repo to remove this config option.
== User Experience ==
There should be no visible change in user experience.
== Dependencies ==
Requires changes in Anaconda (maybe just config?) to set default kargs
and property on ostree repo for new installations.
== Contingency Plan ==
Revert the change before the release.
== Documentation ==
N/A (not a System Wide Change)
== Release Notes ==
TODO
--
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis
1 week, 5 days
VERY late notification emails
by Richard Shaw
I almost wrote this a week ago but decided not to as it's been recently
discussed but this is really annoying. 6 days later is more than useless.
Previously it was blamed, at least partially, on the mass rebuild, but
clearly that should no longer be an issue by now?
I know I can turn them off, but I actually LIKE the messages if they were
delivered promptly.
Is there really nothing we can do about this?
Thanks,
Richard
---------- Forwarded message ---------
From: <notifications(a)fedoraproject.org>
Date: Sun, Feb 27, 2022 at 6:09 PM
Subject: hobbes1069's mingw-fltk-1.3.8-1.fc36 completed
To: <hobbes1069(a)gmail.com>
Notification time stamped 2022-02-21 13:42:00 UTC
hobbes1069's mingw-fltk-1.3.8-1.fc36 completed
http://koji.fedoraproject.org/koji/buildinfo?buildID=1921324
3 weeks, 6 days
Wine MinGW system libraries
by Zebediah Figura
Hello all,
I'm a contributor to the Wine project. To summarize the following mail,
Wine needs special versions of some of its normal dependencies, such as
libfreetype and libgnutls, built using the MinGW cross-compiler, and I'm
sending out a mail to major distributions in order to get some feedback
from our packagers on how these should be built and packaged.
For a long time Wine has built all of its Win32 libraries (DLLs and
EXEs) as ELF binaries. For various reasons related to application
compatibility, we have started building our binaries as PE instead,
using the MinGW cross-compiler. It is our intent to expand this to some
of our dependencies as well. The list of dependencies that we intend to
build using MinGW is not quite fixed yet, but we expect it to include
and be mostly limited to the following:
* libvkd3d
* libFAudio
* libgnutls
* zlib (currently included via manual source import)
* libmpg123
* libgsm
* libpng
* libjpeg-turbo
* libtiff
* libfreetype
* liblcms2
* jxrlib
and dependencies of the above packages (not including CRT dependencies,
which Wine provides).
There is currently some internal discussion about how these dependencies
should be built and linked. There are essentially three questions I see
that need to be resolved, and while these resolutions have a significant
impact on the Wine building and development process, they also have an
impact on distributions, and accordingly I'd like to get input from our
packagers to ensure that their considerations are accurately taken into
account.
(1) Should we build via source import, or link statically, or dynamically?
Static linking and source imports are dispreferred by Fedora [1] [2], as
by many distributions, on the grounds that they cause duplication of
libraries on disk and in memory, and make it harder to update the
libraries in question (see also question 2). They also make building and
bisecting harder.
Note however that if they are linked dynamically, we need to make sure
that we load our packages instead of MinGW builds of open-source
libraries with applications ship with. Accordingly we need each library
to be renamed, and to link to renamed dependencies. For example, if
application X ships with its own copy of libfreetype-6.dll, we need to
make sure that our gdi32.dll links to libwinefreetype-6.dll instead, and
that libwinefreetype-6.dll links to libwineharfbuzz-0.dll and
winezlib.dll. I think, although I haven't completely verified yet, that
this can be done just with build scripts (i.e. no source patches), by
using e.g. --with-zlib=/path/to/winezlib.dll.
Accordingly, although static linking and source imports are generally
disprefered, it may quite likely be preferable in our case. We don't get
the benefits of on-disk deduplication, since Wine is essentially the
only piece of software which needs these libraries.
(2) If we use dynamic libraries, should dependencies be included in the
main wine package, or packaged separately?
This is mostly a question for packagers, although it also relates to (3).
I expect that Fedora (and most distributions) want to answer "packaged
separately" here, on the grounds that this lets them update (say) Wine's
libgnutls separately, and in sync with ELF libgnutls, if some security
fix is needed. There is a snag, though: we need libraries to be copied
into the prefix (there's some internal effort to allow using something
like symlinks instead, but this hard and not done yet). Normally we
perform this copy every time Wine is updated, but if Wine and its
dependencies aren't updated on the same schedule, we may end up loading
an old version of a dependency in the prefix, thus missing the point of
the update.
(3) If dependencies are packaged separately, should Wine build them as
part of its build tree (e.g. using submodules), or find and link
(statically or dynamically) to existing binaries?
Linking to existing binaries is generally preferable: it avoids
duplication on disk; it reduces compile times when compiling a single
package from source (especially the first time). However, we aren't
going to benefit from on-disk duplication. And, most importantly, unlike
with ELF dependencies, there is no standardized way to locate MinGW
libraries—especially if it comes to Wine-specific libraries. We would
need a way for Wine's configure script to find these packages—and
ideally find them automatically, or else fall back to a submodule-based
approach.
If we rely on distributions to provide our dependencies, the best idea I
have here would be something like a x86_64-w64-mingw32-pkg-config. And
if we use shared libraries rather than static, things get worse: we need
to know the exact path of each library and its dependencies so that we
can copy (or symlink) them into a user's WINEPREFIX.
For what it's worth, the current proposed solution (which has the
support of the Wine maintainer) involves source imports and submodules.
There's probably room for changing our approach even after things are
committed, but I'd still like to get early feedback from distributions,
and make sure that their interests are accurately represented, before we
commit. In short, it's not clear whether distributions want their
no-static-library policies to apply to us as well, or whether we're
enough of a special case and would be enough of a pain to package that
they'd rather we deal with the hard parts, and I don't want us to make
any assumptions.
ἔρρωσθε,
Zebediah
[1]
https://docs.fedoraproject.org/en-US/packaging-guidelines/#packaging-stat...
[2] https://fedoraproject.org/wiki/Bundled_Libraries
4 weeks
Do we have any policy for disabling inactive users
by Mattia Verga
Just being paranoid here: do we have any policy / automatism for
disabling "power" users (in packager group or like) which have been
inactive for long time?
I'm no security expert, but an inactive user account may be hacked
without noticing and if such account have powers like being in the
packager group may inject bad things in the distribution.
I also imagine the case where a user no more use their email address and
that become available to someone else. The new user may easily reset the
password and gain access to the old Fedora account (provided that the
old user didn't use 2fa).
Does it make sense to start thinking to prune inactive packagers without
waiting someone to start the "unresponsive maintainer policy"? Maybe a
script could check user activities in src.fedoraproject.org and send a
warning email if no activity is made in one year?
Mattia
4 weeks, 1 day
GNOME (and Cinnamon) issues in Rawhide: status report, including
gnome-bluetooth soname issues
by Adam Williamson
Hey folks! While we're working through fixing this up, I wanted to send
out a note about what's going on.
tl;dr summary: GNOME is broken in Rawhide, and blueberry (Cinnamon's
bluetooth app) may have dep issues temporarily. If you need GNOME to
work, downgrade gnome-shell and mutter. Otherwise, apologies for the
rough ride, hold onto your hats, we're trying to get things fixed up.
Full version: gnome-shell and mutter 42~beta builds were run yesterday.
For Fedora 36 they were done in a sidetag, but for Rawhide, no sidetag
yet existed, so unfortunately they went straight to the main Rawhide
tag and were included in yesterday's compose.
It turns out having those packages at 42~beta but older versions of
other packages gives you a broken GNOME; anyone who updated to Rawhide
yesterday will likely see GNOME crash to the "Oh no!" screen on boot.
To deal with that for now, the best thing to do is to downgrade gnome-
shell and mutter back to the previous builds from Koji.
Since the builds have been in a compose, we can't untag them from
Rawhide, we can only move forwards. So we're trying to build enough of
the rest of GNOME 42~beta to get things working again, but it turns out
quite a lot of stuff needs to be built for that.
A particular pain point is gnome-bluetooth. gnome-shell 42~beta needs
gnome-bluetooth 42, but the new gnome-bluetooth changes the library
API. We noticed that Cinnamon's bluetooth app, blueberry, is built
against the old gnome-bluetooth API, and there are no patches upstream
to handle this.
That left us in an awkward spot. Ideally what should happen is the
gnome-bluetooth soname bump would be announced and Leigh would have a
week to figure out what to do for blueberry/cinnamon. But if we do that
now, GNOME would be broken for a week in Rawhide, which is not ideal.
The solution we decided on is to bump gnome-bluetooth to 42~beta, but
add a gnome-bluetooth3.34 compat package, which should keep blueberry
working until Cinnamon folks can come up with a plan. David King
submitted the package, and I reviewed it:
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=2039855
and it should be built soon. blueberry will need to be rebuilt with its
deps changed a bit, but that should be all. It would be ideal if Leigh
could take over maintenance of this package as long as it's needed.
As things stand right now, gnome-bluetooth 42~beta is built for Rawhide
but gnome-bluetooth3.34 is not yet; depending on exactly when we get it
built it may just miss today's compose, meaning Cinnamon image compose
would be broken for that day, and updates of Rawhide Cinnamon systems
to that day's packages would likely have issues. Most of the other
packages we think we need to build to make GNOME work again are done,
but gnome-control-center is proving tricky; I got some work done
towards getting it to build, but wasn't able to get it all the way, so
I've left a couple of PRs:
https://src.fedoraproject.org/rpms/colord-gtk/pull-request/1
https://src.fedoraproject.org/rpms/gnome-control-center/pull-request/10
and David is going to pick it up and move forward. I'll check back in
in the morning.
Thanks folks, and sorry again for the trouble!
--
Adam Williamson
Fedora QA
IRC: adamw | Twitter: adamw_ha
https://www.happyassassin.net
1 month, 4 weeks
