linux-kernel - Re: double unlock in rng_dev

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Date:	Wed, 23 Dec 2009 23:23:55 +0800
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Dan Carpenter <error27@...il.com>, Matt Mackall <mpm@...enic.com>,
	linux-kernel@...r.kernel.org
Subject: Re: double unlock in rng_dev_read()

On Wed, Dec 23, 2009 at 04:53:36PM +0200, Dan Carpenter wrote:
>
> No no.  I mean when size hits zero we are rng_mutex is unlocked.

Good catch! I'll add this patch to the tree.  Please take a look
at it.  Thanks!

commit f5908267b67917b8cbd98b27fd2be9b5f62ec76f
Author: Herbert Xu <herbert@...dor.apana.org.au>
Date:   Wed Dec 23 23:22:34 2009 +0800

    hwrng: core - Fix double unlock in rng_dev_read
    
    When the loop terminates with size == 0 in rng_dev_read we will
    unlock the rng mutex twice.
    
    Reported-by: Dan Carpenter <error27@...il.com>
    Signed-off-by: Herbert Xu <herbert@...dor.apana.org.au>

diff --git a/drivers/char/hw_random/core.c b/drivers/char/hw_random/core.c
index e989f67..3d9c61e 100644
--- a/drivers/char/hw_random/core.c
+++ b/drivers/char/hw_random/core.c
@@ -158,10 +158,11 @@ static ssize_t rng_dev_read(struct file *filp, char __user *buf,
 			goto out;
 		}
 	}
-out_unlock:
-	mutex_unlock(&rng_mutex);
 out:
 	return ret ? : err;
+out_unlock:
+	mutex_unlock(&rng_mutex);
+	goto out;
 }
 
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