Fix GH-22845: use-after-free with a stashed user-filter bucket brigade#22850
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Fix GH-22845: use-after-free with a stashed user-filter bucket brigade#22850iliaal wants to merge 1 commit into
iliaal wants to merge 1 commit into
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…gade The bucket brigades passed to a user filter's filter() method are allocated on the filter caller's C stack and handed to userland as le_bucket_brigade resources, but userfilter_filter never closed them. A filter that stashed $in or $out (e.g. in a global) kept a resource whose ptr still pointed at the popped stack frame; the stream_bucket_*() functions fetch by resource type only, so a later call dereferenced freed stack. Close both resources after the callback so a stashed copy becomes non-fetchable and throws instead, and wrap the callback in zend_try/zend_catch so the close still runs when the filter bails out (which otherwise longjmps past it and leaves the resource reachable from a shutdown function). Fixes phpGH-22845
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A user stream filter's
filter($in, $out, ...)receives its bucket brigades asle_bucket_brigaderesources, but every caller that dispatches a filter allocates those brigades on its own C stack.userfilter_filteronlyzval_ptr_dtors the argument zvals after the callback and never closes the resources, so a filter that stashes$inor$outkeeps a resource whoseptrstill points at the popped stack frame.stream_bucket_make_writeable()andstream_bucket_append()fetch by resource type only, so reusing a stashed brigade dereferences freed stack (ASAN reports stack-use-after-return). Closing both resources right after the callback invalidates any stashed copy, which then throws a TypeError instead of corrupting memory.The callback is wrapped in
zend_try/zend_catchso the close runs even when the filter bails out (a fatal error would otherwise longjmp past it, leaving the resource fetchable from aregister_shutdown_function).Fixes #22845