netdev - [PATCH] netfilter: nft_bitwise: Adjust parentheses to fix memcmp size argument

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Date:   Wed, 14 Aug 2019 09:58:09 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Pablo Neira Ayuso <pablo@...filter.org>,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Florian Westphal <fw@...len.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com,
        Nathan Chancellor <natechancellor@...il.com>,
        kbuild test robot <lkp@...el.com>
Subject: [PATCH] netfilter: nft_bitwise: Adjust parentheses to fix memcmp size argument

clang warns:

net/netfilter/nft_bitwise.c:138:50: error: size argument in 'memcmp'
call is a comparison [-Werror,-Wmemsize-comparison]
        if (memcmp(&priv->xor, &zero, sizeof(priv->xor) ||
                                      ~~~~~~~~~~~~~~~~~~^~
net/netfilter/nft_bitwise.c:138:6: note: did you mean to compare the
result of 'memcmp' instead?
        if (memcmp(&priv->xor, &zero, sizeof(priv->xor) ||
            ^
                                                       )
net/netfilter/nft_bitwise.c:138:32: note: explicitly cast the argument
to size_t to silence this warning
        if (memcmp(&priv->xor, &zero, sizeof(priv->xor) ||
                                      ^
                                      (size_t)(
1 error generated.

Adjust the parentheses so that the result of the sizeof is used for the
size argument in memcmp, rather than the result of the comparison (which
would always be true because sizeof is a non-zero number).

Fixes: bd8699e9e292 ("netfilter: nft_bitwise: add offload support")
Link: https://github.com/ClangBuiltLinux/linux/issues/638
Reported-by: kbuild test robot <lkp@...el.com>
Signed-off-by: Nathan Chancellor <natechancellor@...il.com>
---
 net/netfilter/nft_bitwise.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nft_bitwise.c b/net/netfilter/nft_bitwise.c
index 1f04ed5c518c..974300178fa9 100644
--- a/net/netfilter/nft_bitwise.c
+++ b/net/netfilter/nft_bitwise.c
@@ -135,8 +135,8 @@ static int nft_bitwise_offload(struct nft_offload_ctx *ctx,
 {
 	const struct nft_bitwise *priv = nft_expr_priv(expr);
 
-	if (memcmp(&priv->xor, &zero, sizeof(priv->xor) ||
-	    priv->sreg != priv->dreg))
+	if (memcmp(&priv->xor, &zero, sizeof(priv->xor)) ||
+	    priv->sreg != priv->dreg)
 		return -EOPNOTSUPP;
 
 	memcpy(&ctx->regs[priv->dreg].mask, &priv->mask, sizeof(priv->mask));
-- 
2.23.0.rc2