Fix GH-9589: dl() segfaults when module is already loaded #9689
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As of PHP 8.2.0, `zend_module_entry` structures are no longer copied, so when a module is permanently loaded, and users try to dynamically load that module again, the structure is corrupted[1], causing a segfault on shutdown. We catch that by checking whether any dynamically loaded module is already loaded, and bailing out in that case without modifying the `zend_module_entry` structure. [1] <php#9589 (comment)>
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Note that this may be applied with or without also applying PR #9648; while that duplicates a bit of code in the former case (where it is not strictly necessary), it still seems to be good practice to catch this condition early, and to fail fast. /cc @arnaud-lb, @morrisonlevi |
cmb69
commented
Oct 7, 2022
| --TEST-- | ||
| dl() segfaults when module is already loaded | ||
| --EXTENSIONS-- | ||
| dl_test |
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It's probably sensible to add a comment regarding the usage of dl_test; actually, it doesn't matter which extension we use for the test, but it is mandatory that it is a shared module; this is always given for dl_test.
arnaud-lb
approved these changes
Oct 7, 2022
iluuu1994
reviewed
Oct 9, 2022
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As of PHP 8.2.0,
zend_module_entrystructures are no longer copied, so when a module is permanently loaded, and users try to dynamically load that module again, the structure is corrupted[1], causing a segfault on shutdown.We catch that by checking whether any dynamically loaded module is already loaded, and bailing out in that case without modifying the
zend_module_entrystructure.[1] #9589 (comment)