Commit a4125514 authored by Richard Levitte's avatar Richard Levitte
Browse files

There's a deadlock when ssleay_rand_bytes is called the first time, since 

it wants to stir the pool using ssleay_rand_add.  This fix provides the
possibility to call ssleay_rand_add inside a locked state by simply telling
it not to do any locking through a static variable.  This isn't the most
elegant way one could do this, but it does retain thread safety during the
stirring process.
parent 033d001e

crypto/rand/md_rand.c

+14 −4
Original line number Diff line number Diff line
@@ -141,6 +141,11 @@ static long md_count[2]={0,0}; 
static double entropy=0;

static int initialized=0;



/* This should be set to 1 only when ssleay_rand_add() is called inside

   an already locked state, so it doesn't try to lock and thereby cause

   a hang.  And it should always be reset back to 0 before unlocking. */

static int add_do_not_lock=0;



#ifdef PREDICT

int rand_predictable=0;

#endif
@@ -201,7 +206,7 @@ static void ssleay_rand_add(const void *buf, int num, double add) 
         * hash function.

	 */



	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	st_idx=state_index;



	/* use our own copies of the counters so that even
@@ -233,7 +238,7 @@ static void ssleay_rand_add(const void *buf, int num, double add) 


	md_count[1] += (num / MD_DIGEST_LENGTH) + (num % MD_DIGEST_LENGTH > 0);



	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);



	for (i=0; i<num; i+=MD_DIGEST_LENGTH)

		{
@@ -275,7 +280,7 @@ static void ssleay_rand_add(const void *buf, int num, double add) 
		}

	memset((char *)&m,0,sizeof(m));



	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	if (!add_do_not_lock) CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	/* Don't just copy back local_md into md -- this could mean that

	 * other thread's seeding remains without effect (except for

	 * the incremented counter).  By XORing it we keep at least as
@@ -286,7 +291,7 @@ static void ssleay_rand_add(const void *buf, int num, double add) 
		}

	if (entropy < ENTROPY_NEEDED) /* stop counting when we have enough */

	    entropy += add;

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	if (!add_do_not_lock) CRYPTO_w_unlock(CRYPTO_LOCK_RAND);

	

#ifndef THREADS	

	assert(md_c[1] == md_count[1]);
@@ -345,6 +350,8 @@ static int ssleay_rand_bytes(unsigned char *buf, int num) 
		RAND_poll();



	CRYPTO_w_lock(CRYPTO_LOCK_RAND);

	add_do_not_lock = 1;	/* Since we call ssleay_rand_add while in

				   this locked state. */



	initialized = 1;

	if (!stirred_pool)
@@ -409,6 +416,9 @@ static int ssleay_rand_bytes(unsigned char *buf, int num) 
	 * are now ours (but other threads may use them too) */



	md_count[0] += 1;



	add_do_not_lock = 0;	/* If this would ever be forgotten, we can

				   expect any evil god to eat our souls. */

	CRYPTO_w_unlock(CRYPTO_LOCK_RAND);



	while (num > 0)