From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 18 Jun 2005 20:51:44 +0000 (+0000)
Subject: When using C-string lookup keys in a dynahash.c hash table, use strncpy()
X-Git-Tag: REL8_0_4~65
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=558ff41f27da0d5a5fc9c0c9a6958bb32035b487;p=thirdparty%2Fpostgresql.git

When using C-string lookup keys in a dynahash.c hash table, use strncpy()
not memcpy() to copy the offered key into the hash table during HASH_ENTER.
This avoids possible core dump if the passed key is located very near the
end of memory.  Per report from Stefan Kaltenbrunner.
---

diff --git a/src/backend/utils/hash/dynahash.c b/src/backend/utils/hash/dynahash.c
index 06e848a47d3..1a54005d2c8 100644
--- a/src/backend/utils/hash/dynahash.c
+++ b/src/backend/utils/hash/dynahash.c
@@ -9,7 +9,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.58 2004/12/31 22:01:37 pgsql Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.58.4.1 2005/06/18 20:51:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -143,6 +143,14 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
 	else
 		hashp->match = memcmp;
 
+	/*
+	 * Similarly, the key-copying function defaults to strncpy() or memcpy().
+	 */
+	if (hashp->hash == string_hash)
+		hashp->keycopy = (HashCopyFunc) strncpy;
+	else
+		hashp->keycopy = memcpy;
+
 	if (flags & HASH_SHARED_MEM)
 	{
 		/*
@@ -657,7 +665,7 @@ hash_search(HTAB *hashp,
 
 			/* copy key into record */
 			currBucket->hashvalue = hashvalue;
-			memcpy(ELEMENTKEY(currBucket), keyPtr, hctl->keysize);
+			hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, hctl->keysize);
 
 			/* caller is expected to fill the data field on return */
 
diff --git a/src/include/utils/hsearch.h b/src/include/utils/hsearch.h
index 9773dc733f3..5a012309ea1 100644
--- a/src/include/utils/hsearch.h
+++ b/src/include/utils/hsearch.h
@@ -7,7 +7,7 @@
  * Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
  * Portions Copyright (c) 1994, Regents of the University of California
  *
- * $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.34 2004/12/31 22:03:46 pgsql Exp $
+ * $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.34.4.1 2005/06/18 20:51:44 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -16,14 +16,25 @@
 
 
 /*
- * Hash and comparison functions must have these signatures.  Comparison
- * functions return zero for match, nonzero for no match.  (The comparison
- * function definition is designed to allow memcmp() and strncmp() to be
- * used directly as key comparison functions.)
+ * Hash functions must have this signature.
  */
 typedef uint32 (*HashValueFunc) (const void *key, Size keysize);
+
+/*
+ * Key comparison functions must have this signature.  Comparison functions
+ * return zero for match, nonzero for no match.  (The comparison function
+ * definition is designed to allow memcmp() and strncmp() to be used directly
+ * as key comparison functions.)
+ */
 typedef int (*HashCompareFunc) (const void *key1, const void *key2,
-											Size keysize);
+								Size keysize);
+
+/*
+ * Key copying functions must have this signature.  The return value is not
+ * used.  (The definition is set up to allow memcpy() and strncpy() to be
+ * used directly.)
+ */
+typedef void *(*HashCopyFunc) (void *dest, const void *src, Size keysize);
 
 /*
  * Space allocation function for a hashtable --- designed to match malloc().
@@ -108,6 +119,7 @@ typedef struct HTAB
 								 * used */
 	char	   *tabname;		/* table name (for error messages) */
 	bool		isshared;		/* true if table is in shared memory */
+	HashCopyFunc keycopy;		/* key copying function */
 } HTAB;
 
 /* Parameter data structure for hash_create */