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To check whether an entity was already parsed, the code previously
tested whether "checked" was non-zero or "children" was non-null. The
"children" check could be unreliable because an empty entity also
results in an empty (NULL) node list. Use a separate flag to make this
check more reliable.
Remove explicit integer casts as final operation
- in assignments
- when passing arguments
- when returning values
Remove casts
- to the same type
- from certain range-bound values
The main motivation is that these explicit casts don't change the result
of operations and only render UBSan's implicit-conversion checks
useless. Removing these casts allows UBSan to detect cases where
truncation or sign-changes occur unexpectedly.
Document some explicit casts as truncating and add a few missing ones.
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.
This is a follow-up to commit 6c283d83.
* buf.c:
(xmlBufGrowInternal):
- Call xmlBufMemoryError() when the buffer size would overflow.
- Account for NUL terminator byte when using XML_MAX_TEXT_LENGTH.
- Do not include NUL terminator byte when returning length.
(xmlBufAdd):
- Call xmlBufMemoryError() when the buffer size would overflow.
* tree.c:
(xmlBufferGrow):
- Call xmlTreeErrMemory() when the buffer size would overflow.
- Do not include NUL terminator byte when returning length.
(xmlBufferResize):
- Update error message in xmlTreeErrMemory() to be consistent
with other similar messages.
(xmlBufferAdd):
- Call xmlTreeErrMemory() when the buffer size would overflow.
(xmlBufferAddHead):
- Add overflow checks similar to those in xmlBufferAdd().
* buf.c:
(xmlBufAddLen):
- Change check for remaining space to account for the NUL
terminator. When adding a length exactly equal to the number
of unused bytes, a NUL terminator was not written.
(xmlBufResize):
- Set `buf->use` and NUL terminator when allocating a new
buffer.
* tree.c:
(xmlBufferResize):
- Set `buf->use` and NUL terminator when allocating a new
buffer.
(xmlBufferAddHead):
- Set NUL terminator before returning early when shifting
contents.
When changing `doc` on an xmlNodePtr or xmlAttrPtr, certain
fields must either be a free-standing string, or they must be
owned by `doc->dict`.
The code to make this change was simply missing, so the crash
happened when an xmlAttrPtr was being torn down after `doc`
changed from non-NULL to NULL, but the `name` field was not
copied. This is scenario 1 below.
The xmlNodePtr->name and xmlNodePtr->content fields are also
fixed at the same time. Note that xmlNodePtr->content is never
added to the dictionary, so NULL is used instead of `newDict` to
force a free-standing copy.
This change covers all cases of dictionary changes:
1. Owned by old dictionary -> NULL new dictionary
- Create free-standing copy of string.
2. Owned by old dictionary -> Non-NULL new dictionary
- Get string from new dictionary pool.
3. Not owned by old dictionary -> Non-NULL new dictionary
- No action necessary (already a free-standing string).
4. Not owned by old dictionary -> NULL new dictionary
- No action necessary (already a free-standing string).
* tree.c:
(_copyStringForNewDictIfNeeded): Add.
(xmlSetTreeDoc):
- Update xmlNodePtr->name, xmlNodePtr->content and
xmlAttrPtr->name when changing the document, if needed.
Found by OSS-Fuzz Issue 45132.
In several places, the code handling string buffers didn't check for
integer overflow or used wrong types for buffer sizes. This could
result in out-of-bounds writes or other memory errors when working on
large, multi-gigabyte buffers.
Thanks to Felix Wilhelm for the report.
Commit 7618a3b1 didn't account for coalesced text nodes.
I think it would be better if xmlStaticCopyNode didn't try to coalesce
text nodes at all. This code path can only be triggered if some other
code doesn't coalesce text nodes properly. In this case, OSS-Fuzz found
such behavior in xinclude.c.
In most places, we really need the double-it scheme to avoid quadratic
behavior. The hybrid scheme still can cause many reallocations and the
bounded scheme doesn't seem to provide meaningful protection in
xmlreader.c.
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.
The children member of entity reference nodes points to the entity
declaration and must never be followed when traversing a tree. In
the worst case, this could lead to an infinite loop.
It's somewhat unclear how moving entity references to other documents
should work exactly. For now we simply set the children pointer to NULL
to avoid a reference to the original document.
Fixes#42.
Client code should never add document nodes as children of other nodes,
but even our own XPointer code has a bug that can produce such trees.
Make sure to really free nested documents. Also see commits 0815302d
and 0762c9b6.
Should fix#269.
I can't see a reason to check attribute content for UTF-8 validity.
Other parts of the API like xmlNewText have always assumed valid UTF-8
as extra checks only slow down processing.
Besides, setting doc->encoding to "ISO-8859-1" seems pointless, and not
freeing the old encoding would cause a memory leak.
Note that this was last changed in 2008 with commit 6f8611fd which
removed unnecessary encoding/decoding steps. Setting attributes should
be even faster now.
Found by OSS-Fuzz.
Add a special case for the predefined XML namespace when looking up DTD
attribute defaults in xmlGetPropNodeInternal to avoid calling
xmlGetNsList.
This fixes quadratic behavior in
- xmlNodeGetBase
- xmlNodeGetLang
- xmlNodeGetSpacePreserve
Found by OSS-Fuzz.
Implement section "4.6 Predefined Entities" of the XML 1.0 spec and
check whether redeclarations of predefined entities match the original
definitions.
Note that some test cases declared
<!ENTITY lt "<">
But the XML spec clearly states that this is illegal:
> If the entities lt or amp are declared, they MUST be declared as
> internal entities whose replacement text is a character reference to
> the respective character (less-than sign or ampersand) being escaped;
> the double escaping is REQUIRED for these entities so that references
> to them produce a well-formed result.
Also fixes#217 but the connection is only tangential. The integer
overflow discovered by fuzzing was more related to the fact that various
parts of the parser disagreed on whether to prefer predefined entities
over their redeclarations. The whole situation is a mess and even
depends on legacy parser options. But now that redeclarations are
validated, it shouldn't make a difference.
As noted in the added comment, this is also one of the cases where
overly defensive checks can hide interesting logic bugs from fuzzers.
A bug related to php DOMDocument:
https://bugs.php.net/bug.php?id=80665
When copy/clone an html document, the xmlDoc->type goes from
XML_HTML_DOCUMENT_NODE to XML_DOCUMENT_NODE.
Apparently, some libxslt RVTs can contain nested document nodes, see
issue #132. I'm not sure how this happens exactly but it can cause a
segfault in xmlFreeNodeList after the changes in commit 0762c9b6.
Make sure not to touch the (nonexistent) `content` member of xmlDocs.
