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authorIlpo Järvinen <ilpo.jarvinen@helsinki.fi>2008-11-25 13:57:01 -0800
committerDavid S. Miller <davem@davemloft.net>2008-11-25 13:57:01 -0800
commit9f782db3f5ceee9aa8de6f853969fbec1b8c6e65 (patch)
treeb798a8186941e5e95796862e3f2520f253791bf4
parentf6486d40b33d1ac2c44c7c55db7edf022d9f4329 (diff)
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: Ilpo Järvinen <ilpo.jarvinen@helsinki.fi> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/skbuff.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 57555a4525da..e03d77d4c1c9 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -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;