Commit 7a67e56f authored by Jarek Poplawski's avatar Jarek Poplawski Committed by David S. Miller
Browse files

net: Fix oops when splicing skbs from a frag_list. 



Lennert Buytenhek wrote:
> Since 4fb66994 ("net: Optimize memory
> usage when splicing from sockets.") I'm seeing this oops (e.g. in
> 2.6.30-rc3) when splicing from a TCP socket to /dev/null on a driver
> (mv643xx_eth) that uses LRO in the skb mode (lro_receive_skb) rather
> than the frag mode:

My patch incorrectly assumed skb->sk was always valid, but for
"frag_listed" skbs we can only use skb->sk of their parent.

Reported-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
Debugged-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
Tested-by: default avatarLennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: default avatarJarek Poplawski <jarkao2@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 93af7aca

net/core/skbuff.c

+14 −13
Original line number Diff line number Diff line
@@ -1365,9 +1365,8 @@ static void sock_spd_release(struct splice_pipe_desc *spd, unsigned int i) 


static inline struct page *linear_to_page(struct page *page, unsigned int *len,

					  unsigned int *offset,

					  struct sk_buff *skb)

					  struct sk_buff *skb, struct sock *sk)

{

	struct sock *sk = skb->sk;

	struct page *p = sk->sk_sndmsg_page;

	unsigned int off;
@@ -1405,13 +1404,14 @@ new_page: 
 */

static inline int spd_fill_page(struct splice_pipe_desc *spd, struct page *page,

				unsigned int *len, unsigned int offset,

				struct sk_buff *skb, int linear)

				struct sk_buff *skb, int linear,

				struct sock *sk)

{

	if (unlikely(spd->nr_pages == PIPE_BUFFERS))

		return 1;



	if (linear) {

		page = linear_to_page(page, len, &offset, skb);

		page = linear_to_page(page, len, &offset, skb, sk);

		if (!page)

			return 1;

	} else
@@ -1442,7 +1442,8 @@ static inline void __segment_seek(struct page **page, unsigned int *poff, 
static inline int __splice_segment(struct page *page, unsigned int poff,

				   unsigned int plen, unsigned int *off,

				   unsigned int *len, struct sk_buff *skb,

				   struct splice_pipe_desc *spd, int linear)

				   struct splice_pipe_desc *spd, int linear,

				   struct sock *sk)

{

	if (!*len)

		return 1;
@@ -1465,7 +1466,7 @@ static inline int __splice_segment(struct page *page, unsigned int poff, 
		/* the linear region may spread across several pages  */

		flen = min_t(unsigned int, flen, PAGE_SIZE - poff);



		if (spd_fill_page(spd, page, &flen, poff, skb, linear))

		if (spd_fill_page(spd, page, &flen, poff, skb, linear, sk))

			return 1;



		__segment_seek(&page, &poff, &plen, flen);
@@ -1481,8 +1482,8 @@ static inline int __splice_segment(struct page *page, unsigned int poff, 
 * pipe is full or if we already spliced the requested length.

 */

static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset,

		      unsigned int *len,

		      struct splice_pipe_desc *spd)

			     unsigned int *len, struct splice_pipe_desc *spd,

			     struct sock *sk)

{

	int seg;
@@ -1492,7 +1493,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
	if (__splice_segment(virt_to_page(skb->data),

			     (unsigned long) skb->data & (PAGE_SIZE - 1),

			     skb_headlen(skb),

			     offset, len, skb, spd, 1))

			     offset, len, skb, spd, 1, sk))

		return 1;



	/*
@@ -1502,7 +1503,7 @@ static int __skb_splice_bits(struct sk_buff *skb, unsigned int *offset, 
		const skb_frag_t *f = &skb_shinfo(skb)->frags[seg];



		if (__splice_segment(f->page, f->page_offset, f->size,

				     offset, len, skb, spd, 0))

				     offset, len, skb, spd, 0, sk))

			return 1;

	}
@@ -1528,12 +1529,13 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset, 
		.ops = &sock_pipe_buf_ops,

		.spd_release = sock_spd_release,

	};

	struct sock *sk = skb->sk;



	/*

	 * __skb_splice_bits() only fails if the output has no room left,

	 * so no point in going over the frag_list for the error case.

	 */

	if (__skb_splice_bits(skb, &offset, &tlen, &spd))

	if (__skb_splice_bits(skb, &offset, &tlen, &spd, sk))

		goto done;

	else if (!tlen)

		goto done;
@@ -1545,14 +1547,13 @@ int skb_splice_bits(struct sk_buff *skb, unsigned int offset, 
		struct sk_buff *list = skb_shinfo(skb)->frag_list;



		for (; list && tlen; list = list->next) {

			if (__skb_splice_bits(list, &offset, &tlen, &spd))

			if (__skb_splice_bits(list, &offset, &tlen, &spd, sk))

				break;

		}

	}



done:

	if (spd.nr_pages) {

		struct sock *sk = skb->sk;

		int ret;



		/*

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