fixes #117
fixes #118
fixes #119
fixes #120
Several other infinite loop bugs were fixed by previous changes.
Include their test files in the test suite.
During parsing of an object, sometimes parts of the object have to be
resolved. An example is stream lengths. If such an object directly or
indirectly points to the object being parsed, it can cause an infinite
loop. Guard against all cases of re-entrant resolution of objects.
This is CVE-2017-9208.
The QPDF library uses object ID 0 internally as a sentinel to
represent a direct object, but prior to this fix, was not blocking
handling of 0 0 obj or 0 0 R as a special case. Creating an object in
the file with 0 0 obj could cause various infinite loops. The PDF spec
doesn't allow for object 0. Having qpdf handle object 0 might be a
better fix, but changing all the places in the code that assumes objid
== 0 means direct would be risky.
This is CVE-2017-9210.
The description string for an error message included unparsing an
object, which is too complex of a thing to try to do while throwing an
exception. There was only one example of this in the entire codebase,
so it is not a pervasive problem. Fixing this eliminated one class of
infinite loop errors.
The 64 Bit file functions are supported by C++-Builder as well and
need to be used, else fseek will error out on larger files than 4 GB
like used in the large file test.
qutil.cc uses strerror to print some exceptions and adds a newline
afterwards, but strerror in Windows already adds one newline at the
end of the message and the additional one from std::endl breaks the
output vs. the expected one.
/dev/null is not portable, so use File::Spec instead, which provides
portable "paths" and especially "nul" on Windows. I changed all places
with hard coded /dev/null to be sure, while I think it only is a
problem in direct system calls, because the other executed commands go
to sh.exe from MSYS which itself should port /dev/null to NUL. The
test still pass, so shouldn't have made any harm...
For non-encrypted files, determinstic ID generation uses file contents
instead of timestamp and file name. At a small runtime cost, this
enables generation of the same /ID if the same inputs are converted in
the same way multiple times.
fix-qdf was previously hard-coding the number of bytes for the f2
field of the xref stream entry. This addresses issue #37. Thanks
aluebcke for reporting.
As reported in issue #40, a call to CryptAcquireContext in
SecureRandomDataProvider fails in a fresh windows install prior to any
user keys being created in AppData\Roaming\Microsoft\Crypto\RSA.
Thanks michalrames.
There have been a few enhancements requested that only affect the qpdf
command line tool and that should be relatively quick to implement.
Work out the details and acknowledge these publicly in the TODO file.
Pushing inherited objects to pages and getting all pages were both
prone to stack overflow infinite loops if there were loops in the
Pages dictionary. There is a general weakness in the code in that any
part of the code that traverses the Pages structure would be prone to
this and would have to implement its own loop detection. A more robust
fix may provide some general method for handling the Pages structure,
but it's probably not worth doing.
Note: addition of *Internal2 private functions was done rather than
changing signatures of existing methods to avoid breaking
compatibility.
Converting a password to an encryption key is supposed to copy up to a
certain number of bytes from a digest. Make sure never to copy more
than the size of the digest.
When checking two objects preceding R while parsing, ensure that the
objects are direct. This avoids stuff like 1 0 obj containing 1 0 R 0 R
from causing an infinite loop in object resolution.
