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Commit 9f782db3 authored by Ilpo Järvinen's avatar Ilpo Järvinen Committed by David S. Miller
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tcp: skb_shift cannot cache frag ptrs past pskb_expand_head 



Since pskb_expand_head creates copy of the shared area we
cannot keep any frag ptr past de-cloning. This fixes the
tcpdump recvfrom -EFAULT problem.

Signed-off-by: default avatarIlpo Järvinen <ilpo.jarvinen@helsinki.fi>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent f6486d40

net/core/skbuff.c

+6 −1
Original line number Diff line number Diff line
@@ -2018,7 +2018,10 @@ void skb_split(struct sk_buff *skb, struct sk_buff *skb1, const u32 len) 
		skb_split_no_header(skb, skb1, len, pos);

}



/* Shifting from/to a cloned skb is a no-go. */

/* Shifting from/to a cloned skb is a no-go.

 *

 * Caller cannot keep skb_shinfo related pointers past calling here!

 */

static int skb_prepare_for_shift(struct sk_buff *skb)

{

	return skb_cloned(skb) && pskb_expand_head(skb, 0, 0, GFP_ATOMIC);
@@ -2070,6 +2073,8 @@ int skb_shift(struct sk_buff *tgt, struct sk_buff *skb, int shiftlen) 
			    skb_prepare_for_shift(tgt))

				return 0;



			/* All previous frag pointers might be stale! */

			fragfrom = &skb_shinfo(skb)->frags[from];

			fragto = &skb_shinfo(tgt)->frags[merge];



			fragto->size += shiftlen;