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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2021-02-02 13:49:08 -0500 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2021-02-02 13:49:08 -0500 |
| commit | 7428469586e837747f86566c790f6ccceac1b1f3 (patch) | |
| tree | a5c4a9e51f1999e799c1c61c4b2abbde423066ce /src/backend/executor/nodeHashjoin.c | |
| parent | be843ce29737ee4752fedabe07a75cf9db1e969f (diff) | |
| download | postgresql-7428469586e837747f86566c790f6ccceac1b1f3.tar.gz postgresql-7428469586e837747f86566c790f6ccceac1b1f3.zip | |
Fix ancient memory leak in contrib/auto_explain.
The ExecutorEnd hook is invoked in a context that could be quite
long-lived, not the executor's own per-query context as I think
we were sort of assuming. Thus, any cruft generated while producing
the EXPLAIN output could accumulate over multiple queries. This can
result in spectacular leakage if log_nested_statements is on, and
even without that I'm surprised nobody complained before.
To fix, just switch into the executor's context so that anything we
allocate will be released when standard_ExecutorEnd frees the executor
state. We might as well nuke the code's retail pfree of the explain
output string, too; that's laughably inadequate to the need.
Japin Li, per report from Jeff Janes. This bug is old, so
back-patch to all supported branches.
Discussion: https://postgr.es/m/CAMkU=1wCVtbeRn0s9gt12KwQ7PLXovbpM8eg25SYocKW3BT4hg@mail.gmail.com
Diffstat (limited to 'src/backend/executor/nodeHashjoin.c')
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