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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.
This commit is contained in:
Tom Lane 2005-06-18 20:51:30 +00:00
parent a8d1075f27
commit 6a6f2d91d4
2 changed files with 32 additions and 8 deletions
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14
src/backend/utils/hash/dynahash.c
View File

@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.61 2005/05/29 04:23:06 tgl Exp $
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.62 2005/06/18 20:51:30 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -167,6 +167,16 @@ 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 (flags & HASH_KEYCOPY)
hashp->keycopy = info->keycopy;
else if (hashp->hash == string_hash)
hashp->keycopy = (HashCopyFunc) strncpy;
else
hashp->keycopy = memcpy;
if (flags & HASH_ALLOC)
hashp->alloc = info->alloc;
else
@ -650,7 +660,7 @@ hash_search(HTAB *hashp,
/* copy key into record */
currBucket->hashvalue = hashvalue;
memcpy(ELEMENTKEY(currBucket), keyPtr, hctl->keysize);
hashp->keycopy(ELEMENTKEY(currBucket), keyPtr, keysize);
/* caller is expected to fill the data field on return */

26
src/include/utils/hsearch.h
View File

@ -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 1.37 2005/06/08 23:02:05 tgl Exp $
* $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.38 2005/06/18 20:51:30 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().
@ -103,6 +114,7 @@ typedef struct HTAB
HASHSEGMENT *dir; /* directory of segment starts */
HashValueFunc hash; /* hash function */
HashCompareFunc match; /* key comparison function */
HashCopyFunc keycopy; /* key copying function */
HashAllocFunc alloc; /* memory allocator */
MemoryContext hcxt; /* memory context if default allocator
* used */
@ -123,6 +135,7 @@ typedef struct HASHCTL
Size entrysize; /* total user element size in bytes */
HashValueFunc hash; /* hash function */
HashCompareFunc match; /* key comparison function */
HashCopyFunc keycopy; /* key copying function */
HashAllocFunc alloc; /* memory allocator */
HASHSEGMENT *dir; /* directory of segment starts */
HASHHDR *hctl; /* location of header in shared mem */
@ -140,6 +153,7 @@ typedef struct HASHCTL
#define HASH_ALLOC 0x100 /* Set memory allocator */
#define HASH_CONTEXT 0x200 /* Set explicit memory context */
#define HASH_COMPARE 0x400 /* Set user defined comparison function */
#define HASH_KEYCOPY 0x800 /* Set user defined key-copying function */
/* max_dsize value to indicate expansible directory */