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Don't use Asserts to check for violations of replication protocol.

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Using an Assert to check the validity of incoming messages is an
extremely poor decision.  In a debug build, it should not be that easy
for a broken or malicious remote client to crash the logrep worker.
The consequences could be even worse in non-debug builds, which will
fail to make such checks at all, leading to who-knows-what misbehavior.
Hence, promote every Assert that could possibly be triggered by wrong
or out-of-order replication messages to a full test-and-ereport.

To avoid bloating the set of messages the translation team has to cope
with, establish a policy that replication protocol violation error
reports don't need to be translated.  Hence, all the new messages here
use errmsg_internal().  A couple of old messages are changed likewise
for consistency.

Along the way, fix some non-idiomatic or outright wrong uses of
hash_search().

Most of these mistakes are new with the "streaming replication"
patch (commit 464824323), but a couple go back a long way.
Back-patch as appropriate.

Discussion: https://postgr.es/m/1719083.1623351052@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2021-06-12 12:59:15 -04:00
parent 1730a3334e
commit 1f280e8331
2 changed files with 9 additions and 2 deletions
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2
src/backend/replication/logical/reorderbuffer.c
View File

@ -1331,7 +1331,7 @@ ReorderBufferBuildTupleCidHash(ReorderBuffer *rb, ReorderBufferTXN *txn)
ent = (ReorderBufferTupleCidEnt *) ent = (ReorderBufferTupleCidEnt *)
hash_search(txn->tuplecid_hash, hash_search(txn->tuplecid_hash,
(void *) &key, (void *) &key,
HASH_ENTER | HASH_FIND, HASH_ENTER,
&found); &found);
if (!found) if (!found)
{ {

9
src/backend/replication/logical/worker.c
View File

@ -501,7 +501,14 @@ apply_handle_commit(StringInfo s)
logicalrep_read_commit(s, &commit_data); logicalrep_read_commit(s, &commit_data);
Assert(commit_data.commit_lsn == remote_final_lsn); if (commit_data.commit_lsn != remote_final_lsn)
ereport(ERROR,
(errcode(ERRCODE_PROTOCOL_VIOLATION),
errmsg_internal("incorrect commit LSN %X/%X in commit message (expected %X/%X)",
(uint32) (commit_data.commit_lsn >> 32),
(uint32) commit_data.commit_lsn,
(uint32) (remote_final_lsn >> 32),
(uint32) remote_final_lsn)));
/* The synchronization worker runs in single transaction. */ /* The synchronization worker runs in single transaction. */
if (IsTransactionState() && !am_tablesync_worker()) if (IsTransactionState() && !am_tablesync_worker())