On Wed, 2019-08-14 at 09:58 -0700, Nathan Chancellor wrote:
> 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@xxxxxxxxx>
> Signed-off-by: Nathan Chancellor <natechancellor@xxxxxxxxx>
> ---
> 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
[]
> @@ -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)
This code should use memchr_inv and not compare against a
static uninitialized struct.
Perhaps linux should introduce and use memcchr like bsd.
or just add something like #define memcchr memchr_inv
