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Commit6a6f2d9

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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 theend of memory. Per report from Stefan Kaltenbrunner.
1 parenta8d1075 commit6a6f2d9

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2 files changed

+32
-8
lines changed

2 files changed

+32
-8
lines changed

‎src/backend/utils/hash/dynahash.c‎

Lines changed: 12 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -9,7 +9,7 @@
99
*
1010
*
1111
* IDENTIFICATION
12-
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.61 2005/05/29 04:23:06 tgl Exp $
12+
* $PostgreSQL: pgsql/src/backend/utils/hash/dynahash.c,v 1.62 2005/06/18 20:51:30 tgl Exp $
1313
*
1414
*-------------------------------------------------------------------------
1515
*/
@@ -167,6 +167,16 @@ hash_create(const char *tabname, long nelem, HASHCTL *info, int flags)
167167
else
168168
hashp->match=memcmp;
169169

170+
/*
171+
* Similarly, the key-copying function defaults to strncpy() or memcpy().
172+
*/
173+
if (flags&HASH_KEYCOPY)
174+
hashp->keycopy=info->keycopy;
175+
elseif (hashp->hash==string_hash)
176+
hashp->keycopy= (HashCopyFunc)strncpy;
177+
else
178+
hashp->keycopy=memcpy;
179+
170180
if (flags&HASH_ALLOC)
171181
hashp->alloc=info->alloc;
172182
else
@@ -650,7 +660,7 @@ hash_search(HTAB *hashp,
650660

651661
/* copy key into record */
652662
currBucket->hashvalue=hashvalue;
653-
memcpy(ELEMENTKEY(currBucket),keyPtr,hctl->keysize);
663+
hashp->keycopy(ELEMENTKEY(currBucket),keyPtr,keysize);
654664

655665
/* caller is expected to fill the data field on return */
656666

‎src/include/utils/hsearch.h‎

Lines changed: 20 additions & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2005, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.37 2005/06/08 23:02:05 tgl Exp $
10+
* $PostgreSQL: pgsql/src/include/utils/hsearch.h,v 1.38 2005/06/18 20:51:30 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -16,14 +16,25 @@
1616

1717

1818
/*
19-
* Hash and comparison functions must have these signatures. Comparison
20-
* functions return zero for match, nonzero for no match. (The comparison
21-
* function definition is designed to allow memcmp() and strncmp() to be
22-
* used directly as key comparison functions.)
19+
* Hash functions must have this signature.
2320
*/
2421
typedefuint32 (*HashValueFunc) (constvoid*key,Sizekeysize);
22+
23+
/*
24+
* Key comparison functions must have this signature. Comparison functions
25+
* return zero for match, nonzero for no match. (The comparison function
26+
* definition is designed to allow memcmp() and strncmp() to be used directly
27+
* as key comparison functions.)
28+
*/
2529
typedefint (*HashCompareFunc) (constvoid*key1,constvoid*key2,
26-
Sizekeysize);
30+
Sizekeysize);
31+
32+
/*
33+
* Key copying functions must have this signature. The return value is not
34+
* used. (The definition is set up to allow memcpy() and strncpy() to be
35+
* used directly.)
36+
*/
37+
typedefvoid*(*HashCopyFunc) (void*dest,constvoid*src,Sizekeysize);
2738

2839
/*
2940
* Space allocation function for a hashtable --- designed to match malloc().
@@ -103,6 +114,7 @@ typedef struct HTAB
103114
HASHSEGMENT*dir;/* directory of segment starts */
104115
HashValueFunchash;/* hash function */
105116
HashCompareFuncmatch;/* key comparison function */
117+
HashCopyFunckeycopy;/* key copying function */
106118
HashAllocFuncalloc;/* memory allocator */
107119
MemoryContexthcxt;/* memory context if default allocator
108120
* used */
@@ -123,6 +135,7 @@ typedef struct HASHCTL
123135
Sizeentrysize;/* total user element size in bytes */
124136
HashValueFunchash;/* hash function */
125137
HashCompareFuncmatch;/* key comparison function */
138+
HashCopyFunckeycopy;/* key copying function */
126139
HashAllocFuncalloc;/* memory allocator */
127140
HASHSEGMENT*dir;/* directory of segment starts */
128141
HASHHDR*hctl;/* location of header in shared mem */
@@ -140,6 +153,7 @@ typedef struct HASHCTL
140153
#defineHASH_ALLOC0x100/* Set memory allocator */
141154
#defineHASH_CONTEXT0x200/* Set explicit memory context */
142155
#defineHASH_COMPARE0x400/* Set user defined comparison function */
156+
#defineHASH_KEYCOPY0x800/* Set user defined key-copying function */
143157

144158

145159
/* max_dsize value to indicate expansible directory */

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