Re: [bug report] rhashtable: Add nested tables

On Thu, Feb 16, 2017 at 03:17:03PM +0300, Dan Carpenter wrote:

Hello Herbert Xu,

This is a semi-automatic email about new static checker warnings.

The patch 40137906c5f5: "rhashtable: Add nested tables" from Feb 11, 
2017, leads to the following Smatch complaint:

lib/rhashtable.c:149 bucket_table_free()
	 warn: variable dereferenced before check 'tbl' (see line 146)

lib/rhashtable.c
   145	{
   146		if (tbl->nest)
                    ^^^^^^^^^
New unchecked dereference.

   147			nested_bucket_table_free(tbl);
   148	
   149		if (tbl)
                    ^^^
Old code checked for NULL.

   150			kvfree(tbl->locks);
   151	

Thanks for catching this.  I checked all the callers and none
of them can provide a NULL pointer so let's just kill the check.

---8<---
Subject: rhashtable: Fix use before NULL check in bucket_table_free

Dan Carpenter reported a use before NULL check bug in the function
bucket_table_free.  In fact we don't need the NULL check at all as
no caller can provide a NULL argument.  So this patch fixes this by
simply removing it.

Reported-by: Dan Carpenter <redacted>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
---

 lib/rhashtable.c |    4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/lib/rhashtable.c b/lib/rhashtable.c
index 172454e..fac1a78 100644
--- a/lib/rhashtable.c
+++ b/lib/rhashtable.c

@@ -146,9 +146,7 @@ static void bucket_table_free(const struct bucket_table *tbl)
 	if (tbl->nest)
 		nested_bucket_table_free(tbl);
 
-	if (tbl)
-		kvfree(tbl->locks);
-
+	kvfree(tbl->locks);
 	kvfree(tbl);
 }
 

-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

From: Herbert Xu <herbert@gondor.apana.org.au>
Date: Sat, 25 Feb 2017 22:38:11 +0800

Subject: rhashtable: Fix use before NULL check in bucket_table_free

Dan Carpenter reported a use before NULL check bug in the function
bucket_table_free.  In fact we don't need the NULL check at all as
no caller can provide a NULL argument.  So this patch fixes this by
simply removing it.

Reported-by: Dan Carpenter <redacted>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Also applied, thanks Herbert.