Commit 677bf08c authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

udp: drop skb extensions before marking skb stateless 



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: 895b5c9f ("netfilter: drop bridge nf reset from nf_reset")
Cc: Paolo Abeni <pabeni@redhat.com>
Reported-by: default avatarByron Stanoszek <gandalf@winds.org>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Acked-by: default avatarPaolo Abeni <pabeni@redhat.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ff08ddba

include/linux/skbuff.h

+6 −0
Original line number Diff line number Diff line
@@ -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)

net/ipv4/udp.c

+22 −5
Original line number Diff line number Diff line
@@ -1297,6 +1297,27 @@ out: 


#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;

}

CRA Git | Maintained and supported by SUSTech CRA and CCSE