deepclone_to_array: resolve INDIRECT slots in retained __serialize() states#23
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…states Before PHP 8.3, Random\Randomizer::__serialize() returns the object's raw property table with only the table itself addref'd; its "engine" entry is an IS_INDIRECT slot pointing into the object (fixed for 8.3 by php-src commit c5fa7696e64, never backported to the by-then security-only 8.2). deepclone_to_array() walks such a state with dc_copy_array(), which passed IS_INDIRECT slots to dc_copy_value() unresolved, so the payload retained pointers into the source object. Once a Randomizer that did not outlive its payload was released, deepclone_from_array() dereferenced freed memory and crashed. Resolve indirects (and skip resolved UNDEF slots) at the start of the walk, exactly like the native serializer and the existing build_scoped_props loop already do.
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… instances on PHP 8.2 (nicolas-grekas) This PR was merged into the 1.x branch. Discussion ---------- [DeepClone] Fix round-tripping short-lived Random\Randomizer instances on PHP 8.2 | Q | A | ------------- | --- | Branch? | 1.x | Bug fix? | yes | New feature? | no | Deprecations? | no | Issues | - | License | MIT This is what has been segfaulting the PHP 8.2 CI jobs since the Randomizer round-trip tests landed in #629 (and what #630 inherits). Minimal reproducer, no polyfill involved, on PHP 8.2.31: ```php $state = (new Random\Randomizer(new Random\Engine\Mt19937(7)))->__serialize(); serialize($state); // SIGSEGV ``` Before PHP 8.3, `Random\Randomizer::__serialize()` returns the object's raw property table with only the table itself addref'd. Its `engine` entry is an `IS_INDIRECT` slot pointing into the object, so once the Randomizer is released the retained state dangles. php-src fixed this for 8.3 by duplicating the table (php/php-src@c5fa7696e64), but 8.2 was already security-only and the fix was never backported; 8.2.31 still crashes. `deepclone_to_array()` retains exactly such a state in its payload, so round-tripping a Randomizer that does not outlive the payload segfaulted on 8.2. There is no copy-based userland fix: plain array reads copy `IS_INDIRECT` slots verbatim instead of resolving them (`gettype()` reports `unknown type`), which is also how the contamination is detected. The serializer is the one userland-reachable code path that resolves these slots, so when a `__serialize()` result is contaminated (checked while the source object is still alive, and only on PHP < 8.3), it is passed through a `serialize()`/`unserialize()` round trip to materialize real values. No new tests: the #629 Randomizer tests are the regression tests; they segfault on PHP 8.2 before this change and pass after (suite verified green on 8.1, 8.2, 8.3 and 8.5). The nested engine becomes a fresh copy rather than a shared instance on the affected versions, matching the already-documented identity behavior of nested `__serialize()` states. Companion extension fix (the with-extensions 8.2 CI legs run the tagged ext via PIE and stay red until it ships in a release): symfony/php-ext-deepclone#23 Perf note: `Random\Randomizer` is special-cased instead of scanned for, after auditing PHP 8.2 core for the pattern: of the internal classes whose `__serialize()` retains the un-duplicated property table (Randomizer, `HashContext`, the Random engines), only Randomizer declares a property, and only declared properties create `IS_INDIRECT` slots (GMP uses the legacy serialize handler, consumed while the object is alive; the date classes already duplicate). Measured on 8.2: no overhead for any other class; Randomizer itself pays one serialize round trip (~190 us for a Mt19937 state), the price of not crashing. On PHP 8.3+ the version guard makes the branch dead code. The trade-off versus scanning every internal state: a hypothetical third-party extension class combining the same pattern with declared properties would keep crashing, as it does today. Companion extension fix (the with-extensions 8.2 CI legs run the tagged ext via PIE, fixed in v0.7.2): symfony/php-ext-deepclone#23 Commits ------- ae1778e [DeepClone] Fix round-tripping short-lived Random\Randomizer instances on PHP 8.2
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Before PHP 8.3,
Random\Randomizer::__serialize()returns the object's raw property table with only the table itself addref'd; itsengineentry is anIS_INDIRECTslot pointing into the object. php-src fixed it for 8.3 by duplicating the table (php/php-src@c5fa7696e64), but the fix was never backported to the by-then security-only 8.2, which still ships the dangling behavior in its final release.deepclone_to_array()walks such a state withdc_copy_array(), which passedIS_INDIRECTslots todc_copy_value()unresolved, so the payload retained pointers into the source object. Once a Randomizer that did not outlive its payload was released,deepclone_from_array()dereferenced freed memory and crashed:This is what segfaults the symfony/polyfill 1.x CI on the PHP 8.2 jobs that install this extension via PIE (the polyfill-only jobs are fixed by the companion PR below); the released v0.7.1 is affected, so those CI legs stay red until this ships in a tagged release.
The fix resolves indirects (and skips resolved UNDEF slots) at the start of the
dc_copy_array()walk, exactly like the native serializer and the extension's existingbuild_scoped_propsloop already do. Verified against a stock PHP 8.2 build: the newdeepclone_randomizer.phptsegfaults before the fix and passes after; the full suite is green on 8.2 and 8.6, and the polyfill test suite passes against the patched extension.Companion polyfill fix: symfony/polyfill#632