v15-0001-Prevent-access-to-other-sessions-temporary-table.patch
text/x-patch
Filename: v15-0001-Prevent-access-to-other-sessions-temporary-table.patch
Type: text/x-patch
Part: 0
Patch
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API reference →
Format: format-patch
Series: patch v15-0001
Subject: Prevent access to other sessions' temporary tables
| File | + | − |
|---|---|---|
| src/backend/storage/aio/read_stream.c | 10 | 0 |
| src/backend/storage/buffer/bufmgr.c | 12 | 2 |
From bd15be73156acc258fd06c7b77a875fb2e154fe8 Mon Sep 17 00:00:00 2001
From: Jim Jones <jim.jones@uni-muenster.de>
Date: Wed, 8 Apr 2026 14:53:06 +0200
Subject: [PATCH v15 1/2] Prevent access to other sessions' temporary tables
---
src/backend/storage/aio/read_stream.c | 10 ++++++++++
src/backend/storage/buffer/bufmgr.c | 14 ++++++++++++--
2 files changed, 22 insertions(+), 2 deletions(-)
diff --git a/src/backend/storage/aio/read_stream.c b/src/backend/storage/aio/read_stream.c
index b6fce4e7cc6..e64c74040e8 100644
--- a/src/backend/storage/aio/read_stream.c
+++ b/src/backend/storage/aio/read_stream.c
@@ -972,6 +972,16 @@ read_stream_begin_relation(int flags,
void *callback_private_data,
size_t per_buffer_data_size)
{
+ /*
+ * Reject attempts to read non-local temporary relations; we would be
+ * likely to get wrong data since we have no visibility into the owning
+ * session's local buffers.
+ */
+ if (RELATION_IS_OTHER_TEMP(rel))
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot access temporary relations of other sessions")));
+
return read_stream_begin_impl(flags,
strategy,
rel,
diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 3cc0b0bdd92..4c464d51f3c 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -795,7 +795,7 @@ PrefetchBuffer(Relation reln, ForkNumber forkNum, BlockNumber blockNum)
if (RELATION_IS_OTHER_TEMP(reln))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot access temporary tables of other sessions")));
+ errmsg("cannot access temporary relations of other sessions")));
/* pass it off to localbuf.c */
return PrefetchLocalBuffer(RelationGetSmgr(reln), forkNum, blockNum);
@@ -936,7 +936,7 @@ ReadBufferExtended(Relation reln, ForkNumber forkNum, BlockNumber blockNum,
if (RELATION_IS_OTHER_TEMP(reln))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot access temporary tables of other sessions")));
+ errmsg("cannot access temporary relations of other sessions")));
/*
* Read the buffer, and update pgstat counters to reflect a cache hit or
@@ -1317,6 +1317,16 @@ ReadBuffer_common(Relation rel, SMgrRelation smgr, char smgr_persistence,
else
persistence = smgr_persistence;
+ /*
+ * Safety net for callers (e.g. via ExtendBufferedRelTo) that reach here
+ * without going through ReadBufferExtended. See ReadBufferExtended for
+ * the primary check and full explanation.
+ */
+ if (rel != NULL && RELATION_IS_OTHER_TEMP(rel))
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot access temporary relations of other sessions")));
+
if (unlikely(mode == RBM_ZERO_AND_CLEANUP_LOCK ||
mode == RBM_ZERO_AND_LOCK))
{
--
2.43.0