RHEL/CentOS 7 shipped with 5.1.2alpha, including the threaded
encoder that is behind #ifdef LZMA_UNSTABLE in the API headers.
In 5.1.2alpha these symbols are under XZ_5.1.2alpha in liblzma.map.
API/ABI compatibility tracking isn't done between development
releases so newer releases didn't have XZ_5.1.2alpha anymore.
Later RHEL/CentOS 7 updated xz to 5.2.2 but they wanted to keep
the exported symbols compatible with 5.1.2alpha. After checking
the ABI changes it turned out that >= 5.2.0 ABI is backward
compatible with the threaded encoder functions from 5.1.2alpha
(but not vice versa as fixes and extensions to these functions
were made between 5.1.2alpha and 5.2.0).
In RHEL/CentOS 7, XZ Utils 5.2.2 was patched with
xz-5.2.2-compat-libs.patch to modify liblzma.map:
- XZ_5.1.2alpha was added with lzma_stream_encoder_mt and
lzma_stream_encoder_mt_memusage. This matched XZ Utils 5.1.2alpha.
- XZ_5.2 was replaced with XZ_5.2.2. It is clear that this was
an error; the intention was to keep using XZ_5.2 (XZ_5.2.2
has never been used in XZ Utils). So XZ_5.2.2 lists all
symbols that were listed under XZ_5.2 before the patch.
lzma_stream_encoder_mt and _mt_memusage are included too so
they are listed both here and under XZ_5.1.2alpha.
The patch didn't add any __asm__(".symver ...") lines to the .c
files. Thus the resulting liblzma.so exports the threaded encoder
functions under XZ_5.1.2alpha only. Listing the two functions
also under XZ_5.2.2 in liblzma.map has no effect without
matching .symver lines.
The lack of XZ_5.2 in RHEL/CentOS 7 means that binaries linked
against unpatched XZ Utils 5.2.x won't run on RHEL/CentOS 7.
This is unfortunate but this alone isn't too bad as the problem
is contained within RHEL/CentOS 7 and doesn't affect users
of other distributions. It could also be fixed internally in
RHEL/CentOS 7.
The second problem is more serious: In XZ Utils 5.2.2 the API
headers don't have #ifdef LZMA_UNSTABLE for obvious reasons.
This is true in RHEL/CentOS 7 version too. Thus now programs
using new APIs can be compiled without an extra #define. However,
the programs end up depending on symbol version XZ_5.1.2alpha
(and possibly also XZ_5.2.2) instead of XZ_5.2 as they would
with an unpatched XZ Utils 5.2.2. This means that such binaries
won't run on other distributions shipping XZ Utils >= 5.2.0 as
they don't provide XZ_5.1.2alpha or XZ_5.2.2; they only provide
XZ_5.2 (and XZ_5.0). (This includes RHEL/CentOS 8 as the patch
luckily isn't included there anymore with XZ Utils 5.2.4.)
Binaries built by RHEL/CentOS 7 users get distributed and then
people wonder why they don't run on some other distribution.
Seems that people have found out about the patch and been copying
it to some build scripts, seemingly curing the symptoms but
actually spreading the illness further and outside RHEL/CentOS 7.
The ill patch seems to be from late 2016 (RHEL 7.3) and in 2017 it
had spread at least to EasyBuild. I heard about the events only
recently. :-(
This commit splits liblzma.map into two versions: one for
GNU/Linux and another for other OSes that can use symbol versioning
(FreeBSD, Solaris, maybe others). The Linux-specific file and the
matching additions to .c files add full compatibility with binaries
that have been built against a RHEL/CentOS-patched liblzma. Builds
for OSes other than GNU/Linux won't get the vaccine as they should
be immune to the problem (I really hope that no build script uses
the RHEL/CentOS 7 patch outside GNU/Linux).
The RHEL/CentOS compatibility symbols XZ_5.1.2alpha and XZ_5.2.2
are intentionally put *after* XZ_5.2 in liblzma_linux.map. This way
if one forgets to #define HAVE_SYMBOL_VERSIONS_LINUX when building,
the resulting liblzma.so.5 will have lzma_stream_encoder_mt@@XZ_5.2
since XZ_5.2 {...} is the first one that lists that function.
Without HAVE_SYMBOL_VERSIONS_LINUX @XZ_5.1.2alpha and @XZ_5.2.2
will be missing but that's still a minor problem compared to
only having lzma_stream_encoder_mt@@XZ_5.1.2alpha!
The "local: *;" line was moved to XZ_5.0 so that it doesn't need
to be moved around. It doesn't matter where it is put.
Having two similar liblzma_*.map files is a bit silly as it is,
at least for now, easily possible to generate the generic one
from the Linux-specific file. But that adds extra steps and
increases the risk of mistakes when supporting more than one
build system. So I rather maintain two files in parallel and let
validate_map.sh check that they are in sync when "make mydist"
is run.
This adds .symver lines for lzma_stream_encoder_mt@XZ_5.2.2 and
lzma_stream_encoder_mt_memusage@XZ_5.2.2 even though these
weren't exported by RHEL/CentOS 7 (only @@XZ_5.1.2alpha was
for these two). I added these anyway because someone might
misunderstand the RHEL/CentOS 7 patch and think that @XZ_5.2.2
(@@XZ_5.2.2) versions were exported too.
At glance one could suggest using __typeof__ to copy the function
prototypes when making aliases. However, this doesn't work trivially
because __typeof__ won't copy attributes (lzma_nothrow, lzma_pure)
and it won't change symbol visibility from hidden to default (done
by LZMA_API()). Attributes could be copied with __copy__ attribute
but that needs GCC 9 and a fallback method would be needed anyway.
This uses __symver__ attribute with GCC >= 10 and
__asm__(".symver ...") with everything else. The attribute method
is required for LTO (-flto) support with GCC. Using -flto with
GCC older than 10 is now broken on GNU/Linux and will not be fixed
(can silently result in a broken liblzma build that has dangerously
incorrect symbol versions). LTO builds with Clang seem to work
with the traditional __asm__(".symver ...") method.
Thanks to Boud Roukema for reporting the problem and discussing
the details and testing the fix.
The previous commit split liblzma.map into liblzma_linux.map and
liblzma_generic.map. This commit updates the CMake build for those.
common_w32res.rc dependency was listed under Linux/FreeBSD while
obviously it belongs to Windows when building a DLL.
These are a minor thing especially since the xz build has
some real problems still like lack of large file support
on 32-bit systems but I'll commit this since the code exists.
Thanks to Jia Tan.
This was supposed to be done in 2020 with 5.2.5 release
already but it was noticed only today. 5.2.5 and 5.2.6
even mention experiemental CMake support in the NEWS entries.
Thanks to Olivier B. for reporting the problem.
The bug was introduced in 352ba2d69a
"Windows: Fix building of resource files when config.h isn't used."
That commit fixed liblzma.dll build with CMake while keeping it
working with Autotools on Windows but the VS project files were
forgotten.
I haven't tested these changes.
Thanks to Olivier B. for reporting the bug and for the initial patch.
This affects the second line in po4a/xz-man.pot. The man pages of
xzdiff, xzgrep, and xzmore are from GNU gzip and under GNU GPLv2+
while the rest of the man pages are in the public domain.
Previously this required using --force but that has other
effects too which might be undesirable. Changing the behavior
of --keep has a small risk of breaking existing scripts but
since this is a fairly special corner case I expect the
likehood of breakage to be low enough.
I think the new behavior is more logical. The only reason for
the old behavior was to be consistent with gzip and bzip2.
Thanks to Vincent Lefevre and Sebastian Andrzej Siewior.
xzgrep wouldn't exit on SIGPIPE or SIGQUIT when it clearly
should have. It's quite possible that it's not perfect still
but at least it's much better.
If multiple exit statuses compete, now it tries to pick
the largest of value.
Some comments were added.
The exit status handling of signals is still broken if the shell
uses values larger than 255 in $? to indicate that a process
died due to a signal ***and*** their "exit" command doesn't take
this into account. This seems to work well with the ksh and yash
versions I tried. However, there is a report in gzip/zgrep that
OpenSolaris 5.11 (not 5.10) has a problem with "exit" truncating
the argument to 8 bits:
https://debbugs.gnu.org/cgi/bugreport.cgi?bug=22900#25
Such a bug would break xzgrep but I didn't add a workaround
at least for now. 5.11 is old and I don't know if the problem
exists in modern descendants, or if the problem exists in other
ksh implementations in use.
I don't know if this can make a difference in the real world
but it looked kind of suspicious (what happens with sed
implementations that cannot process very long lines?).
At least this commit shouldn't make it worse.
It avoids the use of sed for prefixing filenames to output lines.
Using sed for that is slower and prone to security bugs so now
the sed method is only used as a fallback.
This also fixes an actual bug: When grepping a binary file,
GNU grep nowadays prints its diagnostics to stderr instead of
stdout and thus the sed-method for prefixing the filename doesn't
work. So with this commit grepping binary files gives reasonable
output with GNU grep now.
This was inspired by zgrep but the implementation is different.
Also replace one use of expr with printf.
The rationale for LC_ALL=C was already mentioned in
69d1b3fc29 that fixed a security
issue. However, unrelated uses weren't changed in that commit yet.
POSIX says that with sed and such tools one should use LC_ALL=C
to ensure predictable behavior when strings contain byte sequences
that aren't valid multibyte characters in the current locale. See
under "Application usage" in here:
https://pubs.opengroup.org/onlinepubs/9699919799/utilities/sed.html
With GNU sed invalid multibyte strings would work without this;
it's documented in its Texinfo manual. Some other implementations
aren't so forgiving.
Fix handling of "xzgrep -25 foo" (in GNU grep "grep -25 foo" is
an alias for "grep -C25 foo"). xzgrep would treat "foo" as filename
instead of as a pattern. This bug was fixed in zgrep in gzip in 2012.
Add -E, -F, -G, and -P to the "no argument required" list.
Add -X to "argument required" list. It is an
intentionally-undocumented GNU grep option so this isn't
an important option for xzgrep but it seems that other grep
implementations (well, those that I checked) don't support -X
so I hope this change is an improvement still.
grep -d (grep --directories=ACTION) requires an argument. In
contrast to zgrep, I kept -d in the "no argument required" list
because it's not supported in xzgrep (or zgrep). This way
"xzgrep -d" gives an error about option being unsupported instead
of telling that it requires an argument. Both zgrep and xzgrep
tell that it's unsupported if an argument is specified.
Add comments.
Turns out that this is needed for .lzma files as the spec in
LZMA SDK says that end marker may be present even if the size
is stored in the header. Such files are rare but exist in the
real world. The code in liblzma is so old that the spec didn't
exist in LZMA SDK back then and I had understood that such
files weren't possible (the lzma tool in LZMA SDK didn't
create such files).
This modifies the internal API so that LZMA decoder can be told
if EOPM is allowed even when the uncompressed size is known.
It's allowed with .lzma and not with other uses.
Thanks to Karl Beldan for reporting the problem.
Malicious filenames can make xzgrep to write to arbitrary files
or (with a GNU sed extension) lead to arbitrary code execution.
xzgrep from XZ Utils versions up to and including 5.2.5 are
affected. 5.3.1alpha and 5.3.2alpha are affected as well.
This patch works for all of them.
This bug was inherited from gzip's zgrep. gzip 1.12 includes
a fix for zgrep.
The issue with the old sed script is that with multiple newlines,
the N-command will read the second line of input, then the
s-commands will be skipped because it's not the end of the
file yet, then a new sed cycle starts and the pattern space
is printed and emptied. So only the last line or two get escaped.
One way to fix this would be to read all lines into the pattern
space first. However, the included fix is even simpler: All lines
except the last line get a backslash appended at the end. To ensure
that shell command substitution doesn't eat a possible trailing
newline, a colon is appended to the filename before escaping.
The colon is later used to separate the filename from the grep
output so it is fine to add it here instead of a few lines later.
The old code also wasn't POSIX compliant as it used \n in the
replacement section of the s-command. Using \<newline> is the
POSIX compatible method.
LC_ALL=C was added to the two critical sed commands. POSIX sed
manual recommends it when using sed to manipulate pathnames
because in other locales invalid multibyte sequences might
cause issues with some sed implementations. In case of GNU sed,
these particular sed scripts wouldn't have such problems but some
other scripts could have, see:
info '(sed)Locale Considerations'
This vulnerability was discovered by:
cleemy desu wayo working with Trend Micro Zero Day Initiative
Thanks to Jim Meyering and Paul Eggert discussing the different
ways to fix this and for coordinating the patch release schedule
with gzip.
If lzma_index_append() failed (most likely memory allocation failure)
it could have gone unnoticed and the resulting .xz file would have
an incorrect Index. Decompressing such a file would produce the
correct uncompressed data but then an error would occur when
verifying the Index field.
Now it limits the input and output buffer sizes that are
passed to a raw decoder. This way there's no need to check
if the sizes can grow too big or overflow when updating
Compressed Size and Uncompressed Size counts. This also means
that a corrupt file cannot cause the raw decoder to process
useless extra input or output that would exceed the size info
in Block Header (and thus cause LZMA_DATA_ERROR anyway).
More importantly, now the size information is verified more
carefully in case raw decoder returns LZMA_OK. This doesn't
really matter with the current single-threaded .xz decoder
as the errors would be detected slightly later anyway. But
this helps avoiding corner cases in the upcoming threaded
decompressor, and it might help other Block decoder uses
outside liblzma too.
The test files bad-1-lzma2-{9,10,11}.xz test these conditions.
With the single-threaded .xz decoder the only difference is
that LZMA_DATA_ERROR is detected in a difference place now.
This matches xz-utils 5.2.5-2 in Debian.
The translation was done by "bubu", proofread by the debian-l10n-french
mailing list contributors, and submitted to me on the xz-devel mailing
list by Jean-Pierre Giraud. Thanks to everyone!
Previously lzma_lzma_props_encode() and lzma_lzma2_props_encode()
assumed that the options pointers must be non-NULL because the
with these filters the API says it must never be NULL. It is
good to do these checks anyway.
Lasse Collin