2020-12-15 02:07:02

by Colin King

[permalink] [raw]
Subject: [PATCH][next] netfilter: nftables: fix incorrect increment of loop counter

From: Colin Ian King <[email protected]>

The intention of the err_expr cleanup path is to iterate over the
allocated expr_array objects and free them, starting from i - 1 and
working down to the start of the array. Currently the loop counter
is being incremented instead of decremented and also the index i is
being used instead of k, repeatedly destroying the same expr_array
element. Fix this by decrementing k and using k as the index into
expr_array.

Addresses-Coverity: ("Infinite loop")
Fixes: 8cfd9b0f8515 ("netfilter: nftables: generalize set expressions support")
Signed-off-by: Colin Ian King <[email protected]>
---
net/netfilter/nf_tables_api.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index 8d5aa0ac45f4..4186b1e52d58 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -5254,8 +5254,8 @@ static int nft_set_elem_expr_clone(const struct nft_ctx *ctx,
return 0;

err_expr:
- for (k = i - 1; k >= 0; k++)
- nft_expr_destroy(ctx, expr_array[i]);
+ for (k = i - 1; k >= 0; k--)
+ nft_expr_destroy(ctx, expr_array[k]);

return -ENOMEM;
}
--
2.29.2


2020-12-15 14:44:39

by Pablo Neira Ayuso

[permalink] [raw]
Subject: Re: [PATCH][next] netfilter: nftables: fix incorrect increment of loop counter

Hi,

On Mon, Dec 14, 2020 at 11:40:15PM +0000, Colin King wrote:
> From: Colin Ian King <[email protected]>
>
> The intention of the err_expr cleanup path is to iterate over the
> allocated expr_array objects and free them, starting from i - 1 and
> working down to the start of the array. Currently the loop counter
> is being incremented instead of decremented and also the index i is
> being used instead of k, repeatedly destroying the same expr_array
> element. Fix this by decrementing k and using k as the index into
> expr_array.
>
> Addresses-Coverity: ("Infinite loop")
> Fixes: 8cfd9b0f8515 ("netfilter: nftables: generalize set expressions support")
> Signed-off-by: Colin Ian King <[email protected]>

Reviewed-by: Pablo Neira Ayuso <[email protected]>

@Jakub: Would you please take this one into net-next? Thanks!

> ---
> net/netfilter/nf_tables_api.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
> index 8d5aa0ac45f4..4186b1e52d58 100644
> --- a/net/netfilter/nf_tables_api.c
> +++ b/net/netfilter/nf_tables_api.c
> @@ -5254,8 +5254,8 @@ static int nft_set_elem_expr_clone(const struct nft_ctx *ctx,
> return 0;
>
> err_expr:
> - for (k = i - 1; k >= 0; k++)
> - nft_expr_destroy(ctx, expr_array[i]);
> + for (k = i - 1; k >= 0; k--)
> + nft_expr_destroy(ctx, expr_array[k]);
>
> return -ENOMEM;
> }
> --
> 2.29.2
>

2020-12-15 16:23:36

by Pablo Neira Ayuso

[permalink] [raw]
Subject: Re: [PATCH][next] netfilter: nftables: fix incorrect increment of loop counter

On Tue, Dec 15, 2020 at 03:38:30PM +0100, Pablo Neira Ayuso wrote:
> Hi,
>
> On Mon, Dec 14, 2020 at 11:40:15PM +0000, Colin King wrote:
> > From: Colin Ian King <[email protected]>
> >
> > The intention of the err_expr cleanup path is to iterate over the
> > allocated expr_array objects and free them, starting from i - 1 and
> > working down to the start of the array. Currently the loop counter
> > is being incremented instead of decremented and also the index i is
> > being used instead of k, repeatedly destroying the same expr_array
> > element. Fix this by decrementing k and using k as the index into
> > expr_array.
> >
> > Addresses-Coverity: ("Infinite loop")
> > Fixes: 8cfd9b0f8515 ("netfilter: nftables: generalize set expressions support")
> > Signed-off-by: Colin Ian King <[email protected]>
>
> Reviewed-by: Pablo Neira Ayuso <[email protected]>
>
> @Jakub: Would you please take this one into net-next? Thanks!

You marked as "Awaiting Upstream", I'll take care of it.

Thanks.