postgres.git / summary / log / commit / refs

commit    dda622edcdba673e90d7b2cafe747ab78249368b
Author:   Tom Lane <tgl@sss.pgh.pa.us>
Date:     Sun Aug 02 20:49:18 2026 +0000

    Tighten up TS dictionary cache entry creation.
    
    In the not-too-likely scenario where we successfully created a hash
    table entry for a TS dictionary, but then failed to make a small
    memory context for it, we left the hash entry in existence but with
    a garbage value for dictCtx.  This confused the code the next time
    through, leading to a crash.  Rearrange things so that we leave
    the hash entry in a well-defined state with dictCtx == NULL, and
    then the next try knows it still needs to make a memory context.
    
    Reported-by: Alexander Lakhin <exclusion@gmail.com>
    Author: Tom Lane <tgl@sss.pgh.pa.us>
    Discussion: https://postgr.es/m/0f3ddeb5-0dbd-479c-9d0e-ae254758e624@gmail.com
    Backpatch-through: 14


 src/backend/utils/cache/ts_cache.c | 29 +++++++++++++++++++++--------
 1 file changed, 21 insertions(+), 8 deletions(-)

diff --git a/src/backend/utils/cache/ts_cache.c b/src/backend/utils/cache/ts_cache.c
index 384107b6bac..3885c345975 100644
--- a/src/backend/utils/cache/ts_cache.c
+++ b/src/backend/utils/cache/ts_cache.c
@@ -279,37 +279,50 @@ lookup_ts_dictionary_cache(Oid dictId)
 			elog(ERROR, "text search template %u has no lexize method",
 				 template->tmpllexize);
 
+		/*
+		 * OK, create or clear out the hashtable entry
+		 */
 		if (entry == NULL)
 		{
 			bool		found;
 
-			/* Now make the cache entry */
 			entry = (TSDictionaryCacheEntry *)
 				hash_search(TSDictionaryCacheHash,
 							(void *) &dictId,
 							HASH_ENTER, &found);
 			Assert(!found);		/* it wasn't there a moment ago */
 
-			/* Create private memory context the first time through */
+			memset(entry, 0, sizeof(TSDictionaryCacheEntry));
+			entry->dictId = dictId;
+			saveCtx = NULL;
+		}
+		else
+		{
+			saveCtx = entry->dictCtx;	/* could be NULL if we failed before */
+			memset(entry, 0, sizeof(TSDictionaryCacheEntry));
+			entry->dictId = dictId;
+			entry->dictCtx = saveCtx;
+		}
+
+		/*
+		 * Create or clear the entry's private memory context
+		 */
+		if (saveCtx == NULL)
+		{
 			saveCtx = AllocSetContextCreate(CacheMemoryContext,
 											"TS dictionary",
 											ALLOCSET_SMALL_SIZES);
+			entry->dictCtx = saveCtx;
 			MemoryContextCopyAndSetIdentifier(saveCtx, NameStr(dict->dictname));
 		}
 		else
 		{
-			/* Clear the existing entry's private context */
-			saveCtx = entry->dictCtx;
 			/* Don't let context's ident pointer dangle while we reset it */
 			MemoryContextSetIdentifier(saveCtx, NULL);
 			MemoryContextReset(saveCtx);
 			MemoryContextCopyAndSetIdentifier(saveCtx, NameStr(dict->dictname));
 		}
 
-		MemSet(entry, 0, sizeof(TSDictionaryCacheEntry));
-		entry->dictId = dictId;
-		entry->dictCtx = saveCtx;
-
 		entry->lexizeOid = template->tmpllexize;
 
 		if (OidIsValid(template->tmplinit))


[parent: cfc720ef4b1d]