Currently we only ever increment ifd_nesting_level, so this ends up
being a limit on the total number of IFD tags and we regularly get
bug reports of it being exceeded. I think the intention behind this
limit was to prevent recursion stack overflow, and for that we only
need to check actual recursive usage. I've implemented that here,
and dropped the nesting limit down to a smaller value
(which still passes our tests).
However, it seems that we do also need to have a total limit on
the number of tags, as we don't catch some instances of infinite
looping otherwise. Add this as a separate limit with a higher
value, that should hopefully be sufficient.
This is expected to fix a number of bugs:
https://bugs.php.net/bug.php?id=78083https://bugs.php.net/bug.php?id=78701https://bugs.php.net/bug.php?id=79907https://bugs.php.net/bug.php?id=80016
Different manufacturer models may come with a
different endianness (motorola/intel) format. In
order to avoid a big refactor and a gigantic lookup
table, this commit simply attempts to switch the
endianness and proceed when values are acceptable.
Closes GH-5849.
Even if the length of a maker note does not match our expectations
(either because the maker note is corrupted, or because our
expectations do not quite match reality), there is no need to let
parsing fail; we can still go on parsing the other meta information.
* PHP-7.3:
Fixed bug #78910Fix#78878: Buffer underflow in bc_shift_addsub
Fix test
Fix#78862: link() silently truncates after a null byte on Windows
Fix#78863: DirectoryIterator class silently truncates after a null byte
Fix#78943: mail() may release string with refcount==1 twice
* PHP-7.2:
Fixed bug #78910Fix#78878: Buffer underflow in bc_shift_addsub
Fix test
Fix#78862: link() silently truncates after a null byte on Windows
Fix#78863: DirectoryIterator class silently truncates after a null byte
Emitting errors is fairly expensive, to the point that parsing
a file with a huge number of invalid tags can take seconds.
Generating ten thousand errors is unlikely to help anybody, but
constitutes a potential DOS vector.
This fixes two leaks related to duplicate tags, as well as a leak
of zero-length FMT_(S)BYTE with non-null value. This can show up
for MAKERNOTE values where the original length is non-zero, but
the first character is a null byte.
This issue was recently introduced in c739023a50,
when the restriction that components>0 has been relaxed. We now need
to make sure that any tags that expect at least one component check
that this is the case.
Nikita Popov