[NET]: Fix ___pskb_trim when entire frag_list needs dropping

When the trim point is within the head and there is no paged data,
___pskb_trim fails to drop the first element in the frag_list.
This patch fixes this by moving the len <= offset case out of the
page data loop.

This patch also adds a missing kfree_skb on the frag that we just
cloned.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 10 insertions, 4 deletions

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 476aa3978504..d236f02c6467 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -846,7 +846,11 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len)
             unlikely((err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC))))
                 return err;
 
-        for (i = 0; i < nfrags; i++) {
+        i = 0;
+        if (offset >= len)
+                goto drop_pages;
+
+        for (; i < nfrags; i++) {
                 int end = offset + skb_shinfo(skb)->frags[i].size;
 
                 if (end < len) {
@@ -854,9 +858,9 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len)
                         continue;
                 }
 
-                if (len > offset)
-                        skb_shinfo(skb)->frags[i++].size = len - offset;
+                skb_shinfo(skb)->frags[i++].size = len - offset;
 
+drop_pages:
                 skb_shinfo(skb)->nr_frags = i;
 
                 for (; i < nfrags; i++)
@@ -864,7 +868,7 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len)
 
                 if (skb_shinfo(skb)->frag_list)
                         skb_drop_fraglist(skb);
-                break;
+                goto done;
         }
 
         for (fragp = &skb_shinfo(skb)->frag_list; (frag = *fragp);
@@ -879,6 +883,7 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len)
                                 return -ENOMEM;
 
                         nfrag->next = frag->next;
+                        kfree_skb(frag);
                         frag = nfrag;
                         *fragp = frag;
                 }
@@ -897,6 +902,7 @@ int ___pskb_trim(struct sk_buff *skb, unsigned int len)
                 break;
         }
 
+done:
         if (len > skb_headlen(skb)) {
                 skb->data_len -= skb->len - len;
                 skb->len       = len;