Fixes a use-after-free encountered in Symfony's SecurityBundle.
I don't have a reproducer for this, and believe the issue can only
occur if we leak an iterator (the leak is a separate issue).
We should not free the generator iterator here, because we do not
own it. The code that fetched the iterator is responsible for
releasing it. In the rare case where we do hit this code-path,
we cause a use-after-free.
This was needed when php_config.h also declare compatibility
shims for isinf() and friends. These are no longer present in
master, so drop this include.
Unlike the straight unserialize fuzzer, this runs only on HashContexts,
and it does an update and finalize on the contexts it creates.
Co-authored-by: Nikita Popov <nikic@php.net>
* Modify php_hash_ops to contain the algorithm name and
serialize and unserialize methods.
* Implement __serialize and __unserialize magic methods on
HashContext.
Note that serialized HashContexts are not necessarily portable
between PHP versions or from architecture to architecture.
(Most are, though Keccak and slow SHA3s are not.)
An exception is thrown when an unsupported serialization is
attempted.
Because of security concerns, HASH_HMAC contexts are not
currently serializable; attempting to serialize one throws
an exception.
Serialization exposes the state of HashContext memory, so ensure
that memory is zeroed before use by allocating it with a new
php_hash_alloc_context function. Performance impact is
negligible.
Some hash internal states have logical pointers into a buffer,
or sponge, that absorbs input provided in bytes rather than
chunks. The unserialize functions for these hash functions
must validate that the logical pointers are all within bounds,
lest future hash operations cause out-of-bounds memory accesses.
* Adler32, CRC32, FNV, joaat: simple state, no buffer positions
* Gost, MD2, SHA3, Snefru, Tiger, Whirlpool: buffer positions
must be validated
* MD4, MD5, SHA1, SHA2, haval, ripemd: buffer positions encoded
bitwise, forced to within bounds on use; no need to validate
Previously, the Keccak_HashInstance was separately allocated.
This could cause memory leaks on errors. For instance,
in php_hash_do_hash_hmac, the following code cleans up after
a file read error:
if (n < 0) {
efree(context);
efree(K);
zend_string_release(digest);
RETURN_FALSE;
}
This does not call the context's hash_final operation, which
was the only way to free the separately-allocated Keccak state.
The simplest fix is simply to place the Keccak_HashInstance state
inside the context object. Then it doesn't need to be freed.
As a result, there is no need to call hash_final in the
HashContext destructor: HashContexts cannot contain internally
allocated resources.
