In xpath.c there's a lot of code like:
valuePush(ctxt, xmlCacheNewX());
...
valuePop(ctxt);
If xmlCacheNewX fails, no value will be pushed on the stack. If there's
no error check in between, valuePop will pop an unrelated value which
can lead to use-after-free errors.
Instead of trying to fix all call sites, we simply stop popping values
if an error was signaled. This requires to change the CHECK_TYPE macro
which is often used to determine whether a value can be safely popped.
Found with libFuzzer, see #344.
Reporting errors is expensive and some abusive test cases can generate
an error for each invalid input byte. This causes the parser to spend
most of the time with error handling. Limit the number of errors and
warnings to 100.
This commit implements robust detection of entity amplification attacks,
better known as the "billion laughs" attack.
We now limit the size of the document after substitution of entities to
10 times the size before expansion. This guarantees linear behavior by
definition. There already was a similar check before, but the accounting
of "sizeentities" (size of external entities) and "sizeentcopy" (size of
all copies created by entity references) wasn't accurate.
We also need saturation arithmetic since we're historically limited to
"unsigned long" which is 32-bit on many platforms.
A maximum of 10 MB of substitutions is always allowed. This should make
use cases like DITA work which have caused problems in the past.
The old checks based on the number of entities were removed. This is
accounted for by adding a fixed cost to each entity reference.
Entity amplification checks are now enabled even if XML_PARSE_HUGE is
set. This option is mainly used to allow larger text nodes. Most users
were unaware that it also disabled entity expansion checks.
Some of the limits might be adjusted later. If this change turns out to
affect legitimate use cases, we can add a separate parser option to
disable the checks.
Fixes#294.
Fixes#345.
This was an experimental and undocumented micro-optimization for
Windows which apparently required different calling conventions for
variable-argument functions, making it impossible to maintain without
domain knowledge.
Define XML_IGNORE_DEPRECATION_WARNINGS and the corresponding XML_POP_WARNINGS
for Visual Studio, and consequently define XML_IGNORE_FPTR_CAST_WARNINGS so
that we do not get a compiler warning on Visual Studio by doing a
__pragma(warning(pop)) without a corresponding __pragma(warning(push)).
Also correct the documentation a bit for XML_POP_WARNINGS.
We can mark APIs as deprecated using __declspec(deprecated) with Visual Studio
2005 and later, so add a definition of that so that we can help users avoid
using deprecated APIs when using Visual Studio as well.
For the existing GCC definition, check whether we are on GCC 3.1+ before
enabling the definition.
Remove inaccurate xmlParseCheckTransition check.
Remove non-incremental xmlParseGetLasts check.
Add functions that check for several boundary constructs more
accurately, keeping track of progress in ctxt->checkIndex.
Fixes#439.
Private functions were previously declared
- in header files in the root directory
- in public headers guarded with IN_LIBXML
- in libxml.h
- redundantly in source files that used them.
Consolidate all private header files in include/private.
Somewhat misleadingly, the DOC_DISABLE directive only disabled warnings.
Now we really stop the documentation generator from indexing.
This results in additional warnings for xmlThrDef* functions. This should
be fixed by documenting or deprecating them.
Commit 4fd69f3e fixed handling of '<' characters not followed by an
ASCII letter. But a '<!' sequence followed by invalid characters should
be treated as bogus comment and skipped.
Fixes#380.
Add a new configuration flag that controls whether the outdated support
for XPointer locations (ranges and points) is enabled.
--with-xptr-locs # Autotools
LIBXML2_WITH_XPTR_LOCS # CMake
The latest spec for what it essentially an XPath extension seems to be
this working draft from 2002:
https://www.w3.org/TR/xptr-xpointer/
The xpointer() scheme is listed as "being reviewed" in the XPointer
registry since at least 2006. libxml2 seems to be the only modern
software that tries to implement this spec, but the code has many bugs
and quality issues.
The flag defaults to "off" and support for this extensions has to be
requested explicitly. The relevant API functions are deprecated.
- Remove xmlSwitchToEncodingInt which was basically just a wrapper
around xmlSwitchInputEncodingInt.
- Simplify xmlSwitchEncoding.
- Improve error handling in xmlSwitchInputEncodingInt.
- Deprecate xmlSwitchInputEncoding.
These functions shouldn't be part of the public API. Most init
functions are only thread-safe when called from xmlInitParser. Global
variables should only be cleaned up by calling xmlCleanupParser.
This code has been broken and deprecated since version 2.6.0, released
in 2003. Because of a bug in commit 961b535c, DOCBparser.c was never
compiled since 2012. I couldn't find a Debian package using any of its
symbols, so it seems safe to remove this module.
From what I can tell, some really early Cygwin versions from around
1998-2000 used to erroneously define _WIN32. This was eventually fixed,
but these days, the `defined(_WIN32) && !defined(__CYGWIN__)` idiom is
unnecessary.
Now, we only check for __CYGWIN__ in xmlexports.h when deciding whether
to use __declspec.
These functions are only needed internally for validation.
xmlGetRefs is inherently unsafe because the ref table isn't updated
if attributes are removed (unlike the ids table).
None of the Ubuntu 20.04 packages depending on libxml2 use any of these
functions (except xmlFreeRefTable in libxslt), so it seems perfectly
safe to deprecate them.
Remove xmlIsRef and xmlRemoveRef from the Python bindings.
Use a bitmask instead of magic values to
- keep track whether the validation context is part of a parser context
- keep track whether xmlValidateDtdFinal was called
This allows to add addtional flags later.
Note that this deliberately changes the name of a public struct member,
assuming that this was always private data never to be used by client
code.
This file was undocumented and never used anywhere. Maybe users were
supposed to rename this file to xmlversion.h manually. These days, both
CMake and win32/configure.js generate xmlversion.h from xmlversion.h.in,
just like the Autotools build.
