The convention is that
lzma_filter filters[LZMA_FILTERS_MAX + 1];
contains the filters of a single filter chain.
It was so here as well before the commit
d6af7f3470.
It changes "filters" to a ten-element array of filter chains.
It's clearer to call this array-of-arrays "chains".
This also renames "filter_idx" to "chain_idx" which is used
as an index as in chains[chain_idx].
opt_mode == MODE_COMPRESS isn't possible when HAVE_ENCODERS isn't
defined. Thus, when *encoding*, the message about *decoder* memory
usage is possible to show only when both encoder and decoder have
been built.
Since the message is shown only at V_DEBUG, skip the memusage
calculation if verbosity level isn't high enough.
Fixes: 5f0c5a0438
This was added to xz in 02e3505991
but I forgot to do the same in xzdec.
The Landlock sandbox in xzdec could be stricter as now it's
active only for the last file being decompressed. In xz,
read-only sandbox is used for multi-file case. On the other hand,
xz doesn't go to the strictest mode when processing the last file
when more than one file was specified; xzdec does.
Clang 17 with -fsanitize=address,undefined:
src/liblzma/common/filter_common.c:366:8: runtime error:
call to function encoder_find through pointer to incorrect
function type 'const lzma_filter_coder *(*)(unsigned long)'
src/liblzma/common/filter_encoder.c:187: note:
encoder_find defined here
Use a wrapper function to get the correct type neatly.
This reduces the number of casts needed too.
This issue could be a problem with control flow integrity (CFI)
methods that check the function type on indirect function calls.
Fixes: 3b34851de1
It's undefined behavior. The result wasn't ever used as it occurred
in the last iteration of a loop.
Clang 17 with -fsanitize=address,undefined:
$ src/xz/xz --block-list=123
src/xz/args.c:164:12: runtime error: applying non-zero offset 1
to null pointer
Fixes: 88ccf47205
Co-authored-by: Sam James <sam@gentoo.org>
If the arguments to lzma_index_decoder() or lzma_index_buffer_decode()
were such that LZMA_PROG_ERROR was returned, the lzma_index **i
argument wasn't touched even though the API docs say that *i = NULL
is done if an error occurs. This obviously won't be done even now
if i == NULL but otherwise it is best to do it due to the wording
in the API docs.
In practice this matters very little: The problem can occur only
if the functions are called with invalid arguments, that is,
the calling application must already have a bug.
The __builtin_bswapXX from GCC and Clang are preferred when
they are available. This can allow compilers to emit the x86 MOVBE
instruction instead of doing a load + byteswap as two instructions
(which would happen if the byteswapping is done in inline asm).
bswap16, bswap32, and bswap64 exist in system headers on *BSDs
and Darwin. #defining bswap16 on NetBSD results in a warning about
macro redefinition. It's safest to avoid this namespace conflict
completely.
No OS supported by tuklib_integer.h uses byteswapXX names and
a web search doesn't immediately find any obvious danger of
namespace conflicts. So let's try these still-pretty-short names
for the macros.
Thanks to Sam James for pointing out the compiler warning on
NetBSD 10.0.
The API docs clearly say that if error_pos isn't NULL then *error
is always set on any error. However, it wasn't touched if str == NULL
or filters == NULL or unsupported flags were specified.
Fixes: cedeeca2ea
It is logical why it cannot know for sure that the value has
to be at most 4 if it is less than 16.
The x86 filter is based on a very old LZMA SDK version. Newer
ones have quite a different implementation for the same filter.
Thanks to Sam James.
On macOS, we get:
```
signals.c: In function 'signals_init':
signals.c:76:17: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
76 | sigaddset(&hooked_signals, sigs[i]);
| ^~~~~~~~~
signals.c:81:17: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
81 | sigaddset(&hooked_signals, message_progress_sigs[i]);
| ^~~~~~~~~
signals.c:86:9: error: conversion to 'sigset_t' {aka 'unsigned int'} from 'int' may change the sign of the result [-Werror=sign-conversion]
86 | sigaddset(&hooked_signals, SIGTSTP);
| ^~~~~~~~~
```
We use `int` for `hooked_signals` but we can't just cast to whatever
`sigset_t` is because `sigset_t` is an opaque type. It's an unsigned int
on macOS. On macOS, `sigaddset` is implemented as a macro.
Just suppress -Wsign-conversion for `signals_init` for macOS given
there's no real nice way of fixing this.
This is *NOT* done for security reasons even though the backdoor
relied on the ifunc code. Instead, the reason is that in this
project ifunc provides little benefits but it's quite a bit of
extra code to support it. The only case where ifunc *might* matter
for performance is if the CRC functions are used directly by an
application. In normal compression use it's completely irrelevant.
While the backdoor was inactive (and thus harmless) without inserting
a small trigger code into the build system when the source package was
created, it's good to remove this anyway:
- The executable payloads were embedded as binary blobs in
the test files. This was a blatant violation of the
Debian Free Software Guidelines.
- On machines that see lots bots poking at the SSH port, the backdoor
noticeably increased CPU load, resulting in degraded user experience
and thus overwhelmingly negative user feedback.
- The maintainer who added the backdoor has disappeared.
- Backdoors are bad for security.
This reverts the following without making any other changes:
6e636819 Tests: Update two test files.
a3a29bbd Tests: Test --single-stream can decompress bad-3-corrupt_lzma2.xz.
0b4ccc91 Tests: Update RISC-V test files.
8c9b8b20 liblzma: Fix typos in crc32_fast.c and crc64_fast.c.
82ecc538 liblzma: Fix false Valgrind error report with GCC.
cf44e4b7 Tests: Add a few test files.
3060e107 Tests: Use smaller dictionary size in RISC-V test files.
e2870db5 Tests: Add two RISC-V Filter test files.
The RISC-V test files also have real content that tests the filter
but the real content would fit into much smaller files. A generator
program would need to be available as well.
Thanks to Andres Freund for finding and reporting it and making
it public quickly so others could act without a delay.
See: https://www.openwall.com/lists/oss-security/2024/03/29/4
Lasse Collin
Sam James