On Sun, Feb 16, 2014 at 01:09:43PM +0100, Nikolay Aleksandrov wrote: > On 02/16/2014 01:07 PM, Patrick McHardy wrote: > > On Sun, Feb 16, 2014 at 12:54:40PM +0100, Nikolay Aleksandrov wrote: > >> Add a check if payload's offset is a power of 2 when selecting ops. > >> The fast ops were meant for well aligned offsets, also this fixes a > >> small bug when using unaligned offset and length of 3 which causes > >> only 1 byte to be loaded because the fast ops are chosen. > >> > >> Signed-off-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxx> > >> --- > >> I broke the line since it was >80 chars. > >> This patch applies to Dave's -net tree. > >> > >> net/netfilter/nft_payload.c | 4 +++- > >> 1 file changed, 3 insertions(+), 1 deletion(-) > >> > >> diff --git a/net/netfilter/nft_payload.c b/net/netfilter/nft_payload.c > >> index a2aeb31..15a3dcb 100644 > >> --- a/net/netfilter/nft_payload.c > >> +++ b/net/netfilter/nft_payload.c > >> @@ -135,7 +135,9 @@ nft_payload_select_ops(const struct nft_ctx *ctx, > >> if (len == 0 || len > FIELD_SIZEOF(struct nft_data, data)) > >> return ERR_PTR(-EINVAL); > >> > >> - if (len <= 4 && IS_ALIGNED(offset, len) && base != NFT_PAYLOAD_LL_HEADER) > >> + if (len <= 4 && IS_ALIGNED(offset, len) && > >> + base != NFT_PAYLOAD_LL_HEADER && > >> + !(offset & (offset - 1))) > > > > Small cosmetic note: we have is_power_of_2(), which does exactly this. > > > I didn't choose is_power_of_2 because it also checks if x is != 0, so I > thought we can allow for 0 offset with the fast ops. Sorry for not noticing before, but I'd propose to check length for power of two. We're trying to determine whether the load is well aligned. > > > Also I think the more logical order would be: > > > > len <= 4 && is_power_of_2 && IS_ALIGNED && base ... > > > Okay :-) > > >> return &nft_payload_fast_ops; > >> else > >> return &nft_payload_ops; > >> -- > >> 1.8.4.2 -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
