From e75b5c85549df2294dfaee988be9c7b2a08f0b85 Mon Sep 17 00:00:00 2001 From: Noah Misch Date: Sat, 21 Jan 2023 06:08:00 -0800 Subject: [PATCH] Reject CancelRequestPacket having unexpected length. When the length was too short, the server read outside the allocation. That yielded the same log noise as sending the correct length with (backendPID,cancelAuthCode) matching nothing. Change to a message about the unexpected length. Given the attacker's lack of control over the memory layout and the general lack of diversity in memory layouts at the code in question, we doubt a would-be attacker could cause a segfault. Hence, while the report arrived via security@postgresql.org, this is not a vulnerability. Back-patch to v11 (all supported versions). Andrey Borodin, reviewed by Tom Lane. Reported by Andrey Borodin. --- src/backend/postmaster/postmaster.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index a8b3f5000c..6a8cda6332 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -2000,6 +2000,13 @@ ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done) if (proto == CANCEL_REQUEST_CODE) { + if (len != sizeof(CancelRequestPacket)) + { + ereport(COMMERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid length of startup packet"))); + return STATUS_ERROR; + } processCancelRequest(port, buf); /* Not really an error, but we don't want to proceed further */ return STATUS_ERROR;