netdev - Re: [PATCH RFC net-next] net: Assert napi_gro

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 31 Jul 2015 13:14:07 -0700
From:	Tom Herbert <tom@...bertland.com>
To:	Florian Fainelli <f.fainelli@...il.com>
Cc:	Linux Kernel Network Developers <netdev@...r.kernel.org>,
	Herbert Xu <herbert@...dor.apana.org.au>, daniel@...earbox.net,
	Eric Dumazet <edumazet@...gle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH RFC net-next] net: Assert napi_gro_cb size against skb->cb[]

On Fri, Jul 31, 2015 at 11:51 AM, Florian Fainelli <f.fainelli@...il.com> wrote:
> On 64-bits hosts, napi_gro_cb is 48 bytes, which is exactly the size of
> skb->cb[], while on 32-bits hosts it is 36 bytes, but if it were to
> grow, we would not be catching a size inflation as we should.
>
> Make sure that we have enough room for a napi_gro_cb to be hosted in
> skb->cb[], and put this build-time assertion in skb_gro_reset_offset()
> since this function is invoked by the GRO layers entry points.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  net/core/dev.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/net/core/dev.c b/net/core/dev.c
> index 4870c3556a5a..20bc82604b75 100644
> --- a/net/core/dev.c
> +++ b/net/core/dev.c
> @@ -4115,6 +4115,8 @@ static void skb_gro_reset_offset(struct sk_buff *skb)
>         const struct skb_shared_info *pinfo = skb_shinfo(skb);
>         const skb_frag_t *frag0 = &pinfo->frags[0];
>
> +       BUILD_BUG_ON(sizeof(skb->cb) < sizeof(struct napi_gro_cb));
> +
Maybe sizeof(struct napi_gro_cb) > sizeof(skb->cb) since this about
napi_gro_cb being too big, not cb being too small.

>         NAPI_GRO_CB(skb)->data_offset = 0;
>         NAPI_GRO_CB(skb)->frag0 = NULL;
>         NAPI_GRO_CB(skb)->frag0_len = 0;
> --
> 2.1.0
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html