Backport: Ban role pg_signal_backend from more superuser backend types. #1504
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Cherry-picked from https://git.postgresql.org/cgit/postgresql.git/commit/?id=3a9b18b3095366cd0c4305441d426d04572d88c1 Documentation says it cannot signal "a backend owned by a superuser". On the contrary, it could signal background workers, including the logical replication launcher. It could signal autovacuum workers and the autovacuum launcher. Block all that. Signaling autovacuum workers and those two launchers doesn't stall progress beyond what one could achieve other ways. If a cluster uses a non-core extension with a background worker that does not auto-restart, this could create a denial of service with respect to that background worker. A background worker with bugs in its code for responding to terminations or cancellations could experience those bugs at a time the pg_signal_backend member chooses. Back-patch to v11 (all supported versions). Reviewed by Jelte Fennema-Nio. Reported by Hemanth Sandrana and Mahendrakar Srinivasarao. Security: CVE-2023-5870
reshke
added
type: Backport
type: Security
x4m
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Dec 23, 2025
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Cherry-picked from
https://git.postgresql.org/cgit/postgresql.git/commit/?id=3a9b18b3095366cd0c4305441d426d04572d88c1
Documentation says it cannot signal "a backend owned by a superuser". On the contrary, it could signal background workers, including the logical replication launcher. It could signal autovacuum workers and the autovacuum launcher. Block all that. Signaling autovacuum workers and those two launchers doesn't stall progress beyond what one could achieve other ways. If a cluster uses a non-core extension with a background worker that does not auto-restart, this could create a denial of service with respect to that background worker. A background worker with bugs in its code for responding to terminations or cancellations could experience those bugs at a time the pg_signal_backend member chooses. Back-patch to v11 (all supported versions).
Reviewed by Jelte Fennema-Nio. Reported by Hemanth Sandrana and Mahendrakar Srinivasarao.
Security: CVE-2023-5870