Commit ed940700 authored by Sebastian Andrzej Siewior's avatar Sebastian Andrzej Siewior Committed by Herbert Xu
Browse files

crypto: ansi_prng - Use just a BH lock 



The current code uses a mix of sping_lock() & spin_lock_irqsave(). This can
lead to deadlock with the correct timming & cprng_get_random() + cprng_reset()
sequence.
I've converted them to bottom half locks since all three user grab just a BH
lock so this runs probably in softirq :)

Signed-off-by: default avatarSebastian Andrzej Siewior <sebastian@breakpoint.cc>
Acked-by: default avatarNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent a68f6610

crypto/ansi_cprng.c

+4 −5
Original line number Diff line number Diff line
@@ -187,7 +187,6 @@ static int _get_more_prng_bytes(struct prng_context *ctx) 
/* Our exported functions */

static int get_prng_bytes(char *buf, size_t nbytes, struct prng_context *ctx)

{

	unsigned long flags;

	unsigned char *ptr = buf;

	unsigned int byte_count = (unsigned int)nbytes;

	int err;
@@ -196,7 +195,7 @@ static int get_prng_bytes(char *buf, size_t nbytes, struct prng_context *ctx) 
	if (nbytes < 0)

		return -EINVAL;



	spin_lock_irqsave(&ctx->prng_lock, flags);

	spin_lock_bh(&ctx->prng_lock);



	err = -EINVAL;

	if (ctx->flags & PRNG_NEED_RESET)
@@ -268,7 +267,7 @@ empty_rbuf: 
		goto remainder;



done:

	spin_unlock_irqrestore(&ctx->prng_lock, flags);

	spin_unlock_bh(&ctx->prng_lock);

	dbgprint(KERN_CRIT "returning %d from get_prng_bytes in context %p\n",

		err, ctx);

	return err;
@@ -287,7 +286,7 @@ static int reset_prng_context(struct prng_context *ctx, 
	int rc = -EINVAL;

	unsigned char *prng_key;



	spin_lock(&ctx->prng_lock);

	spin_lock_bh(&ctx->prng_lock);

	ctx->flags |= PRNG_NEED_RESET;



	prng_key = (key != NULL) ? key : (unsigned char *)DEFAULT_PRNG_KEY;
@@ -332,7 +331,7 @@ static int reset_prng_context(struct prng_context *ctx, 
	rc = 0;

	ctx->flags &= ~PRNG_NEED_RESET;

out:

	spin_unlock(&ctx->prng_lock);

	spin_unlock_bh(&ctx->prng_lock);



	return rc;

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