[Bridge] [patch] netfilter: prevent harmless integer overflow
Pablo Neira Ayuso
pablo at netfilter.org
Thu Jun 20 10:23:52 UTC 2013
On Tue, Jun 18, 2013 at 10:46:03AM +0300, Dan Carpenter wrote:
> This overflow is harmless because a few lines later we check:
>
> if (num_counters != t->private->nentries) {
>
> But it still upsets the static checkers.
>
> Signed-off-by: Dan Carpenter <dan.carpenter at oracle.com>
>
> diff --git a/net/bridge/netfilter/ebtables.c b/net/bridge/netfilter/ebtables.c
> index 3d110c4..141350e 100644
> --- a/net/bridge/netfilter/ebtables.c
> +++ b/net/bridge/netfilter/ebtables.c
> @@ -1278,6 +1278,8 @@ static int do_update_counters(struct net *net, const char *name,
>
> if (num_counters == 0)
> return -EINVAL;
> + if (num_counters > INT_MAX / sizeof(*tmp))
> + return -ENOMEM;
This is artificially limiting to INT_MAX / sizeof(struct counters).
Before this patch, the limit is UINT_MAX / sizeof(struct counters). I
think it's very unlikely to hit such a limit though, but as you
mentioned we cover the overflow already. Adding it to calm down a
static checker sound a bit too much for me.
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