[PATCH] net/netfilter: Fix use uninitialized warn in nft_range_eval()

[PATCH] net/netfilter: Fix use uninitialized warn in nft_range_eval()

[Shuah Khan]

Fix the following warn:

   CC [M]  net/netfilter/nft_range.o
8601,8605c9105
 net/netfilter/nft_range.c: In function ‘nft_range_eval’:
 net/netfilter/nft_range.c:45:5: warning: ‘mismatch’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   if (mismatch)
      ^

Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>
---
 net/netfilter/nft_range.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netfilter/nft_range.c b/net/netfilter/nft_range.c
index c6d5358..fe5f69b 100644
--- a/net/netfilter/nft_range.c
+++ b/net/netfilter/nft_range.c
@@ -28,7 +28,7 @@ static void nft_range_eval(const struct nft_expr *expr,
 			 const struct nft_pktinfo *pkt)
 {
 	const struct nft_range_expr *priv = nft_expr_priv(expr);
-	bool mismatch;
+	bool mismatch = false;
 	int d1, d2;
 
 	d1 = memcmp(&regs->data[priv->sreg], &priv->data_from, priv->len);
-- 
2.9.3

Re: [PATCH] net/netfilter: Fix use uninitialized warn in nft_range_eval()

[Pablo Neira Ayuso]

On Mon, Nov 07, 2016 at 08:41:14AM -0700, Shuah Khan wrote:
> Fix the following warn:
> 
>    CC [M]  net/netfilter/nft_range.o
> 8601,8605c9105
>  net/netfilter/nft_range.c: In function ‘nft_range_eval’:
>  net/netfilter/nft_range.c:45:5: warning: ‘mismatch’ may be used uninitialized in this function [-Wmaybe-uninitialized]
>    if (mismatch)
>       ^

You probably using an old tree snapshot? This was already fixed by:

commit d2e4d593516e877f1f6fb40031eb495f36606e16
Author: Arnd Bergmann <arnd@arndb.de>
Date:   Tue Oct 18 00:05:30 2016 +0200

    netfilter: nf_tables: avoid uninitialized variable warning

    The newly added nft_range_eval() function handles the two possible
    nft range operations, but as the compiler warning points out,
    any unexpected value would lead to the 'mismatch' variable being
    used without being initialized: