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The userspace wrapper guard only compared the filename being opened against the currently open one, so a wrapper whose stream_open() opens a different path at every level, an incrementing counter in the URL for instance, recursed without bound and exhausted the C stack. Add a per-request nesting counter shared by user_wrapper_opener() and user_wrapper_opendir() that rejects opens past 64 levels with the existing "infinite recursion prevented" error, decremented on every exit including the bailout branch. Sibling audit, no other entry point nests user-wrapper opens: stat, unlink, rename, mkdir, rmdir and the metadata handlers do not recurse through fopen/opendir.
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The userspace wrapper guard only compared the filename being opened against the currently open one, so a wrapper whose stream_open() opens a different path at every level, an incrementing counter in the URL for instance, recursed until the C stack ran out. A per-request nesting counter shared by user_wrapper_opener() and user_wrapper_opendir() now rejects opens past 64 levels with the existing "infinite recursion prevented" error, and is decremented on every exit including the bailout branch. The counter sits at the end of php_file_globals so the struct keeps its layout for extensions built against the 8.4 header.