Fix typo in pg_srand48 (srand48 in older branches).

tglsfdc · tglsfdc · commit 48e4b8dc08ea · 2011-09-03T16:17:34.000-04:00
"&gt;" should be "&gt;&gt;".  This typo results in failure to use all of the bits
of the provided seed.

This might rise to the level of a security bug if we were relying on
srand48 for any security-critical purposes, but we are not --- in fact,
it's not used at all unless the platform lacks srandom(), which is
improbable.  Even on such a platform the exposure seems minimal.

Reported privately by Andres Freund.
diff --git a/src/port/erand48.c b/src/port/erand48.c
@@ -96,7 +96,7 @@ pg_srand48(long seed)
 {
 	_rand48_seed[0] = RAND48_SEED_0;
 	_rand48_seed[1] = (unsigned short) seed;
-	_rand48_seed[2] = (unsigned short) (seed > 16);
+	_rand48_seed[2] = (unsigned short) (seed >> 16);
 	_rand48_mult[0] = RAND48_MULT_0;
 	_rand48_mult[1] = RAND48_MULT_1;
 	_rand48_mult[2] = RAND48_MULT_2;

Original file line number	Diff line number	Diff line change
`@@ -96,7 +96,7 @@ pg_srand48(long seed)`
`96`	`96`	`{`
`97`	`97`	`_rand48_seed[0] = RAND48_SEED_0;`
`98`	`98`	`_rand48_seed[1] = (unsigned short) seed;`
`99`		`- _rand48_seed[2] = (unsigned short) (seed > 16);`
	`99`	`+ _rand48_seed[2] = (unsigned short) (seed >> 16);`
`100`	`100`	`_rand48_mult[0] = RAND48_MULT_0;`
`101`	`101`	`_rand48_mult[1] = RAND48_MULT_1;`
`102`	`102`	`_rand48_mult[2] = RAND48_MULT_2;`