From: Paolo Abeni <pabeni@redhat.com>
To: Florian Westphal <fw@strlen.de>, netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, Byron Stanoszek <gandalf@winds.org>
Subject: Re: [PATCH net] udp: drop skb extensions before marking skb stateless
Date: Thu, 21 Nov 2019 15:39:45 +0100 [thread overview]
Message-ID: <65c66f8c860b7fc0c01f65feecae08aebb5cb0c9.camel@redhat.com> (raw)
In-Reply-To: <20191121055623.20952-1-fw@strlen.de>
On Thu, 2019-11-21 at 06:56 +0100, Florian Westphal wrote:
> Once udp stack has set the UDP_SKB_IS_STATELESS flag, later skb free
> assumes all skb head state has been dropped already.
>
> This will leak the extension memory in case the skb has extensions other
> than the ipsec secpath, e.g. bridge nf data.
>
> To fix this, set the UDP_SKB_IS_STATELESS flag only if we don't have
> extensions or if the extension space can be free'd.
>
> Fixes: 895b5c9f206eb7d25dc1360a ("netfilter: drop bridge nf reset from nf_reset")
> Cc: Paolo Abeni <pabeni@redhat.com>
> Reported-by: Byron Stanoszek <gandalf@winds.org>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
> include/linux/skbuff.h | 6 ++++++
> net/ipv4/udp.c | 27 ++++++++++++++++++++++-----
> 2 files changed, 28 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
> index 64a395c7f689..8688f7adfda7 100644
> --- a/include/linux/skbuff.h
> +++ b/include/linux/skbuff.h
> @@ -4169,12 +4169,18 @@ static inline void skb_ext_reset(struct sk_buff *skb)
> skb->active_extensions = 0;
> }
> }
> +
> +static inline bool skb_has_extensions(struct sk_buff *skb)
> +{
> + return unlikely(skb->active_extensions);
> +}
> #else
> static inline void skb_ext_put(struct sk_buff *skb) {}
> static inline void skb_ext_reset(struct sk_buff *skb) {}
> static inline void skb_ext_del(struct sk_buff *skb, int unused) {}
> static inline void __skb_ext_copy(struct sk_buff *d, const struct sk_buff *s) {}
> static inline void skb_ext_copy(struct sk_buff *dst, const struct sk_buff *s) {}
> +static inline bool skb_has_extensions(struct sk_buff *skb) { return false; }
> #endif /* CONFIG_SKB_EXTENSIONS */
>
> static inline void nf_reset_ct(struct sk_buff *skb)
> diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
> index 1d58ce829dca..447defbfccdd 100644
> --- a/net/ipv4/udp.c
> +++ b/net/ipv4/udp.c
> @@ -1297,6 +1297,27 @@ int udp_sendpage(struct sock *sk, struct page *page, int offset,
>
> #define UDP_SKB_IS_STATELESS 0x80000000
>
> +/* all head states (dst, sk, nf conntrack) except skb extensions are
> + * cleared by udp_rcv().
> + *
> + * We need to preserve secpath, if present, to eventually process
> + * IP_CMSG_PASSSEC at recvmsg() time.
> + *
> + * Other extensions can be cleared.
> + */
> +static bool udp_try_make_stateless(struct sk_buff *skb)
> +{
> + if (!skb_has_extensions(skb))
> + return true;
> +
> + if (!secpath_exists(skb)) {
> + skb_ext_reset(skb);
> + return true;
> + }
> +
> + return false;
> +}
> +
> static void udp_set_dev_scratch(struct sk_buff *skb)
> {
> struct udp_dev_scratch *scratch = udp_skb_scratch(skb);
> @@ -1308,11 +1329,7 @@ static void udp_set_dev_scratch(struct sk_buff *skb)
> scratch->csum_unnecessary = !!skb_csum_unnecessary(skb);
> scratch->is_linear = !skb_is_nonlinear(skb);
> #endif
> - /* all head states execept sp (dst, sk, nf) are always cleared by
> - * udp_rcv() and we need to preserve secpath, if present, to eventually
> - * process IP_CMSG_PASSSEC at recvmsg() time
> - */
> - if (likely(!skb_sec_path(skb)))
> + if (udp_try_make_stateless(skb))
> scratch->_tsize_state |= UDP_SKB_IS_STATELESS;
> }
Acked-by: Paolo Abeni <pabeni@redhat.com>
next prev parent reply other threads:[~2019-11-21 14:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-19 16:09 Kernel 5.4 regression - memory leak in network layer Byron Stanoszek
2019-11-19 16:22 ` Florian Westphal
2019-11-20 20:28 ` Florian Westphal
2019-11-21 0:15 ` Byron Stanoszek
2019-11-21 5:30 ` Florian Westphal
2019-11-21 5:56 ` [PATCH net] udp: drop skb extensions before marking skb stateless Florian Westphal
2019-11-21 14:39 ` Paolo Abeni [this message]
2019-11-21 20:46 ` Byron Stanoszek
2019-11-21 23:04 ` David Miller
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