Commit e9fa4f7b authored by Herbert Xu's avatar Herbert Xu Committed by David S. Miller
Browse files

[INET]: Use pskb_trim_unique when trimming paged unique skbs 



The IPv4/IPv6 datagram output path was using skb_trim to trim paged
packets because they know that the packet has not been cloned yet
(since the packet hasn't been given to anything else in the system).

This broke because skb_trim no longer allows paged packets to be
trimmed.  Paged packets must be given to one of the pskb_trim functions
instead.

This patch adds a new pskb_trim_unique function to cover the IPv4/IPv6
datagram output path scenario and replaces the corresponding skb_trim
calls with it.

Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent dcb7cd97

include/linux/skbuff.h

+15 −0
Original line number Diff line number Diff line
@@ -1039,6 +1039,21 @@ static inline int pskb_trim(struct sk_buff *skb, unsigned int len) 
	return (len < skb->len) ? __pskb_trim(skb, len) : 0;

}



/**

 *	pskb_trim_unique - remove end from a paged unique (not cloned) buffer

 *	@skb: buffer to alter

 *	@len: new length

 *

 *	This is identical to pskb_trim except that the caller knows that

 *	the skb is not cloned so we should never get an error due to out-

 *	of-memory.

 */

static inline void pskb_trim_unique(struct sk_buff *skb, unsigned int len)

{

	int err = pskb_trim(skb, len);

	BUG_ON(err);

}



/**

 *	skb_orphan - orphan a buffer

 *	@skb: buffer to orphan

net/ipv4/ip_output.c

+2 −2
Original line number Diff line number Diff line
@@ -947,7 +947,7 @@ alloc_new_skb: 
				skb_prev->csum = csum_sub(skb_prev->csum,

							  skb->csum);

				data += fraggap;

				skb_trim(skb_prev, maxfraglen);

				pskb_trim_unique(skb_prev, maxfraglen);

			}



			copy = datalen - transhdrlen - fraggap;
@@ -1142,7 +1142,7 @@ ssize_t ip_append_page(struct sock *sk, struct page *page, 
					data, fraggap, 0);

				skb_prev->csum = csum_sub(skb_prev->csum,

							  skb->csum);

				skb_trim(skb_prev, maxfraglen);

				pskb_trim_unique(skb_prev, maxfraglen);

			}



			/*

net/ipv6/ip6_output.c

+1 −1
Original line number Diff line number Diff line
@@ -1095,7 +1095,7 @@ alloc_new_skb: 
				skb_prev->csum = csum_sub(skb_prev->csum,

							  skb->csum);

				data += fraggap;

				skb_trim(skb_prev, maxfraglen);

				pskb_trim_unique(skb_prev, maxfraglen);

			}

			copy = datalen - transhdrlen - fraggap;

			if (copy < 0) {

CRA Git | Maintained and supported by SUSTech CRA and CCSE