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When the callback denies the push, or throws and leaves the return value undefined, libcurl destroys the easy handle itself. The wrapper kept a stale ch->cp after a throw, and in both cases never released the CurlHandle it had just created, so each denied push leaked one wrapper and permanently bumped the parent's clone counter. Clear ch->cp and drop the callback's reference instead. curl_free_obj() now keys its early return on ch->clone, which is unset only when the constructor failed, so a handle whose easy handle libcurl already freed still releases its handlers when its last reference goes, including when the callback kept it.
When a CURLMOPT_PUSHFUNCTION callback keeps the pushed CurlHandle and denies the push, libcurl frees the easy handle and the wrapper is left with ch->cp set to NULL. curl_easy_reset() and curl_easy_duphandle() do not accept a NULL handle, so curl_reset(), curl_copy_handle() and clone on the kept handle crash. Skip the libcurl reset and take the existing duplication failure exits when there is no easy handle.
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It seems that |
bukka
marked this pull request as draft
November 7, 2026 15:07
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Please create draft if it's not ready for review (e.g. based on another PR). |
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Closing: #23850 now gives a denied handle the callback keeps a fresh easy handle, so curl_reset(), curl_copy_handle(), clone and curl_pause() no longer see a NULL one. The test moved there. |
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Depends on #23850 and is stacked on its branch, so the first commit here is that PR's; only the second commit is new. When a CURLMOPT_PUSHFUNCTION callback keeps the pushed handle and denies the push, libcurl frees the easy handle and the CurlHandle is left with a NULL ch->cp. curl_reset(), curl_copy_handle() and clone pass that NULL to curl_easy_reset() and curl_easy_duphandle() and segfault. This predates #23850 (reproduced on 5714009); the other CurlHandle entry points already fail cleanly without an easy handle.
The test depends on the dtor change in #23850: without it the kept handle's handlers leak and a debug build reports it.
Not included: curl_getinfo() with CURLINFO_CERTINFO leaks the array it initialised when curl_easy_getinfo() fails, reachable through the same kept handle. That is a separate fix.